Physics objectives

Here are 20 objective Physics questions along with their answers, with a one-line gap between each question:

1. What is the SI unit of electric current? Answer: Ampere
2. Which physical quantity is measured in Hertz (Hz)? Answer: Frequency
3. What is the value of the acceleration due to gravity (g) on the surface of the Earth? Answer: 9.8 \text{ m/s}^2
4. Which law states that "pressure applied to an enclosed fluid is transmitted undiminished to every part of the fluid"? Answer: Pascal's Law
5. What type of mirror is commonly used as a rear-view mirror in vehicles? Answer: Convex mirror
6. What is the speed of light in a vacuum? Answer: 3 \times 10^8 \text{ m/s}
7. Which instrument is used to measure atmospheric pressure? Answer: Barometer
8. What is the phenomenon of splitting of white light into its seven constituent colors called? Answer: Dispersion of light
9. Which scientist formulated the three laws of motion? Answer: Sir Isaac Newton
10. What is the unit of electrical resistance? Answer: Ohm (\Omega)
11. Which form of energy is stored in a stretched rubber band? Answer: Potential energy
12. What is the boiling point of water on the Kelvin scale? Answer: 373.15 \text{ K} (or 373 \text{ K})
13. Which color of light deviates the least through a prism? Answer: Red
14. What device converts mechanical energy into electrical energy? Answer: Dynamo or Generator
15. What is the primary source of energy for the sun and stars? Answer: Nuclear fusion
16. Which quantity remains constant in a simple harmonic motion (SHM)? Answer: Total mechanical energy
17. What lens is used to correct myopia (nearsightedness)? Answer: Concave lens
18. What is the SI unit of work and energy? Answer: Joule
19. Which subatomic particle has a negative electric charge? Answer: Electron
20. What is the frequency range of audible sound for humans? Answer: 20 \text{ Hz} to 20,000 \text{ Hz}

objective physics

1.  ​What is the S.I. unit of electric current? (A) Volt (B) Ampere (C) Ohm (D) Watt Answer: (B) Ampere
2. ​Which mirror is used by dentists to view an enlarged image of teeth? (A) Convex mirror (B) Plane mirror (C) Concave mirror (D) Cylindrical mirror Answer: (C) Concave mirror
3. ​The focal length of a spherical mirror with a radius of curvature of 40 cm is: (A) 20 cm (B) 40 cm (C) 80 cm (D) 10 cm Answer: (A) 20 cm
4. ​The least distance of distinct vision for a normal human eye is: (A) 25 m (B) 2.5 cm (C) 25 cm (D) Infinity Answer: (C) 25 cm
5. ​Which instrument is used to measure potential difference across a circuit? (A) Ammeter (B) Voltmeter (C) Galvanometer (D) Rheostat Answer: (B) Voltmeter
6. ​The splitting of white light into its seven component colors by a glass prism is called: (A) Reflection (B) Refraction (C) Dispersion (D) Scattering Answer: (C) Dispersion
7. ​A concave lens always forms an image that is: (A) Real and inverted (B) Virtual and erect (C) Real and magnified (D) Virtual and inverted Answer: (B) Virtual and erect
8. ​The S.I. unit of power of a lens is: (A) Meter (B) Watt (C) Diopter (D) Joule Answer: (C) Diopter
9. ​The resistance of a conductor is inversely proportional to its: (A) Length (B) Area of cross-section (C) Temperature (D) Resistivity Answer: (B) Area of cross-section
10. ​A person unable to see nearby objects clearly suffers from: (A) Myopia (B) Hypermetropia (C) Presbyopia (D) Cataract Answer: (B) Hypermetropia
11. ​The commercial unit of electrical energy (1 kWh) is equal to: (A) 3.6 x 10^6 J (B) 3.6 x 10^5 J (C) 1000 J (D) 360 J Answer: (A) 3.6 x 10^6 J
12. ​The magnetic field lines inside a current-carrying straight solenoid are: (A) Circular (B) Parabolic (C) Parallel straight lines (D) Spiral Answer: (C) Parallel straight lines
13. ​A device that converts mechanical energy into electrical energy is called a: (A) Electric motor (B) Electric generator (C) Transformer (D) Galvanometer Answer: (B) Electric generator
14. ​According to Fleming's Left-Hand Rule, the forefinger points in the direction of: (A) Electric current (B) Magnetic field (C) Force on the conductor (D) Motion of the conductor Answer: (B) Magnetic field
15. ​The blue color of the sky is primarily due to: (A) Reflection of light (B) Refraction of light (C) Scattering of light (D) Total internal reflection Answer: (C) Scattering of light 

Objective Physics

Here are 10 MCQs covering Class 10 Physics topics common to both Bihar Board and CBSE (Light, Electricity, Magnetism):

**1.** The power of a lens is +2.0 D. The lens is:

a) Concave, f = 50 cm

b) Convex, f = 50 cm

c) Concave, f = 200 cm

d) Convex, f = 20 cm

**Answer: b**

**2.** SI unit of electrical resistivity is:

a) Ohm

b) Ohm-metre

c) Ohm/metre

d) Siemens

**Answer: b**

**3.** Which mirror is used as a rear-view mirror in vehicles?

a) Plane mirror

b) Concave mirror

c) Convex mirror

d) Cylindrical mirror

**Answer: c**

**4.** The phenomenon responsible for the blue color of the sky is:

a) Reflection

b) Refraction

c) Scattering

d) Dispersion

**Answer: c**

**5.** Two resistors of 4 Ω and 6 Ω are connected in parallel. The equivalent resistance is:

a) 10 Ω

b) 2.4 Ω

c) 5 Ω

d) 24 Ω

**Answer: b**

**6.** The magnetic field lines inside a current-carrying solenoid are:

a) Circular

b) Parallel straight lines

c) Zero

d) Radiating outward

**Answer: b**

**7.** A person cannot see distant objects clearly. This defect is called:

a) Hypermetropia

b) Myopia

c) Presbyopia

d) Astigmatism

**Answer: b**

**8.** Which device converts mechanical energy into electrical energy?

a) Electric motor

b) Generator

c) Transformer

d) Battery

**Answer: b**

**9.** The refractive index of a medium depends on:

a) Color of light

b) Nature of medium

c) Both a and b

d) Neither a nor b

**Answer: c**

**10.** Fuse wire used in domestic circuits is made of an alloy with:

a) High resistance and high melting point

b) Low resistance and low melting point

c) Low resistance and high melting point

d) High resistance and low melting point

**Answer: b**

Want me to make more sets by chapter (Light, Electricity, Magnetism separately) for PYQBank.in, or format these into a doc/spreadsheet?

5 numericals of physics.

Here are **5 essential numerical problems** from the Light and Electricity chapters of Class 10 Physics, broken down step-by-step using standard formulas.

Light: Reflection and Refraction**

Problem 1: Concave Mirror (Mirror Formula)**

An object 2\text{ cm} high is placed at a distance of 15\text{ cm} in front of a concave mirror of focal length 10\text{ cm}. Find the position, size, and nature of the image.

**Solution:**

 * **Given:**

   * Height of object (h_o) = +2\text{ cm}

   * Object distance (u) = -15\text{ cm} *(by sign convention)*

   * Focal length (f) = -10\text{ cm} *(concave mirror)*

 * **Step 1: Find Image Distance (v) using Mirror Formula**

   

 * **Step 2: Find Image Height (h_i) using Magnification**

   

 * **Conclusion:**

   * **Position:** 30\text{ cm} in front of the mirror.

   * **Nature:** Real and inverted (indicated by negative sign in h_i and v).

   * **Size:** Magnified (4\text{ cm} tall).

#### **Problem 2: Convex Lens & Lens Power**

A convex lens forms a real and inverted image of a needle at a distance of 50\text{ cm} from it. Where is the needle placed in front of the convex lens if the image is equal to the size of the object? Also, find the power of the lens.

**Solution:**

 * **Given:**

   * Image distance (v) = +50\text{ cm} *(real image formed by convex lens)*

   * Magnification (m) = -1 *(since image is real, inverted, and equal in size to object)*

 * **Step 1: Find Object Distance (u)**

   

 * **Step 2: Find Focal Length (f) using Lens Formula**

   

 * **Step 3: Calculate Power (P)**

   

 * **Conclusion:** The needle is placed at **50\text{ cm}** in front of the lens, and the power of the lens is **+4\text{ D}**.

### **Electricity**

#### **Problem 3: Equivalent Resistance & Circuit Current**

Three resistors of 5\ \Omega, 10\ \Omega, and 30\ \Omega are connected in parallel across a 12\text{ V} battery. Calculate:

 1. Total effective resistance of the circuit.

 2. Total current flowing in the circuit.

**Solution:**

 * **Given:** R_1 = 5\ \Omega, R_2 = 10\ \Omega, R_3 = 30\ \Omega, V = 12\text{ V}

 * **Step 1: Total Parallel Resistance (R_p)**

   

 * **Step 2: Calculate Total Current (I) using Ohm's Law**

   

 * **Conclusion:** Total effective resistance is **3\ \Omega** and the total current is **4\text{ A}**.

#### **Problem 4: Resistivity Formula**

A copper wire of length 2\text{ m} has a cross-sectional area of 1.7 \times 10^{-6}\text{ m}^2. If the resistivity of copper is 1.7 \times 10^{-8}\ \Omega\cdot\text{m}, calculate the resistance of the wire.

**Solution:**

 * **Given:**

   * Length (l) = 2\text{ m}

   * Area (A) = 1.7 \times 10^{-6}\text{ m}^2

   * Resistivity (\rho) = 1.7 \times 10^{-8}\ \Omega\cdot\text{m}

 * **Step 1: Apply Formula R = \rho \frac{l}{A}**

   

 * **Conclusion:** The resistance of the wire is **0.02\ \Omega** (or 2 \times 10^{-2}\ \Omega).

#### **Problem 5: Commercial Unit of Electric Energy (Joule's Heating)**

An electric refrigerator rated 400\text{ W} operates 8 hours/day. What is the cost of the energy to operate it for 30 days at ₹ 3.00 per \text{kWh}?

**Solution:**

 * **Given:**

   * Power (P) = 400\text{ W} = 0.4\text{ kW}

   * Time per day (t_1) = 8\text{ hours}

   * Total duration (D) = 30\text{ days}

   * Rate = ₹ 3.00 per unit (\text{kWh})

 * **Step 1: Calculate Total Hours (t)**

   

 * **Step 2: Calculate Total Energy Consumed (E)**

   

 * **Step 3: Calculate Total Cost**

   

 * **Conclusion:** The cost of energy for 30 days is **₹ 288**.

Objective questions of Physics

Here are 15 objective questions (Multiple Choice) based on Physics syllabus, complete with answers and explanations, spaced out as requested:

**1. What is the power of a convex lens having a focal length of 0.5\text{ m}?**

(a) +1\text{ D}

(b) +2\text{ D}

(c) -2\text{ D}

(d) +0.5\text{ D}

**Answer:** (b) +2\text{ D}

*(Explanation: Power P = \frac{1}{f\text{ (in meters)}} = \frac{1}{0.5} = +2\text{ D})*

**2. Which phenomenon of light is responsible for the twinkling of stars?**

(a) Dispersion of light

(b) Atmospheric refraction

(c) Total internal reflection

(d) Scattering of light

**Answer:** (b) Atmospheric refraction

**3. The SI unit of electric resistance is:**

(a) Ampere

(b) Volt

(c) Ohm

(d) Joule

**Answer:** (c) Ohm

**4. When light enters from air into glass, its wavelength:**

(a) Increases

(b) Decreases

(c) Remains unchanged

(d) First increases then decreases

**Answer:** (b) Decreases

*(Explanation: Light slows down in a denser medium, so its wavelength decreases while frequency remains constant.)*

**5. A spherical mirror whose reflecting surface is curved outwards is called a:**

(a) Concave mirror

(b) Convex mirror

(c) Plane mirror

(d) Parabolic mirror

**Answer:** (b) Convex mirror

**6. What is the minimum distance of distinct vision for a normal human eye?**

(a) 25\text{ m}

(b) 2.5\text{ cm}

(c) 25\text{ cm}

(d) Infinity

**Answer:** (c) 25\text{ cm}

**7. How much current will an electric bulb draw from a 220\text{ V} source, if the resistance of the bulb filament is 1200\ \Omega?**

(a) 0.18\text{ A}

(b) 5.45\text{ A}

(c) 0.5\text{ A}

(d) 2.2\text{ A}

**Answer:** (a) 0.18\text{ A}

*(Explanation: According to Ohm's Law, I = \frac{V}{R} = \frac{220}{1200} \approx 0.183\text{ A})*

**8. The strength of the magnetic field inside a long straight current-carrying solenoid is:**

(a) Zero

(b) Decreases as we move towards its ends

(c) Increases as we move towards its ends

(d) Is the same at all points

**Answer:** (d) Is the same at all points

**9. The focal length of a plane mirror is:**

(a) Zero

(b) Positive

(c) Negative

(d) Infinity

**Answer:** (d) Infinity

**10. Which rule is used to determine the direction of force experienced by a current-carrying conductor in a magnetic field?**

(a) Right-hand thumb rule

(b) Fleming's left-hand rule

(c) Fleming's right-hand rule

(d) Ampere's circuital rule

**Answer:** (b) Fleming's left-hand rule

**11. Red light is used in danger signals because:**

(a) It is scattered the most by air particles

(b) It is scattered the least by air particles

(c) It travels slowest in air

(d) It has the shortest wavelength

**Answer:** (b) It is scattered the least by air particles

**12. If the resistance of a resistor is halved and the voltage remains constant, the power dissipated will:**

(a) Be halved

(b) Double

(c) Quadruple

(d) Remain the same

**Answer:** (b) Double

*(Explanation: Power P = \frac{V^2}{R}. If R becomes \frac{R}{2}, power doubles.)*

**13. Defect of vision known as hypermetropia (farsightedness) can be corrected using a:**

(a) Concave lens

(b) Convex lens

(c) Cylindrical lens

(d) Bifocal lens

**Answer:** (b) Convex lens

**14. A device that converts electrical energy into mechanical energy is a:**

(a) Generator

(b) Galvanometer

(c) Electric motor

(d) Ammeter

**Answer:** (c) Electric motor

**15. If three resistors of resistances 2\ \Omega, 3\ \Omega, and 6\ \Omega are connected in parallel, their equivalent resistance is:**

(a) 11\ \Omega

(b) 1\ \Omega

(c) 0.5\ \Omega

(d) 2\ \Omega

**Answer:** (b) 1\ \Omega

*(Explanation: \frac{1}{R_{\text{eq}}} = \frac{1}{2} + \frac{1}{3} + \frac{1}{6} = \frac{3 + 2 + 1}{6} = \frac{6}{6} = 1\ \Omega)*

10 th physics objective questions with answer

Here are **15 high-yield objective questions (MCQs)** with immediate answers for Class 10 Physics, covering key topics from Light, Electricity, Magnetism, and Human Eye:

### **Class 10 Physics - Objective Questions**

**1. The SI unit of electric current is:**

(A) Volt

(B) Ampere

(C) Ohm

(D) Joule

**Answer: (B) Ampere**

**2. Which mirror is used by dentists to view a large image of teeth?**

(A) Convex mirror

(B) Plane mirror

(C) Concave mirror

(D) Cylindrical mirror

**Answer: (C) Concave mirror**

**3. The focal length of a spherical mirror with a radius of curvature of 30\text{ cm} is:**

(A) 15\text{ cm}

(B) 30\text{ cm}

(C) 60\text{ cm}

(D) 10\text{ cm}

**Answer: (A) 15\text{ cm}** *(Since f = \frac{R}{2})*

**4. The least distance of distinct vision for a normal human eye is:**

(A) 25\text{ m}

(B) 2.5\text{ cm}

(C) 25\text{ cm}

(D) Infinity

**Answer: (C) 25\text{ cm}**

**5. Which component is used to measure electrical potential difference across a circuit?**

(A) Ammeter

(B) Voltmeter

(C) Rheostat

(D) Galvanometer

**Answer: (B) Voltmeter**

**6. The splitting of white light into its seven constituent colors through a prism is called:**

(A) Reflection

(B) Refraction

(C) Dispersion

(D) Total Internal Reflection

**Answer: (C) Dispersion**

**7. A concave lens always forms an image that is:**

(A) Real and inverted

(B) Virtual and erect

(C) Real and magnified

(D) Virtual and inverted

**Answer: (B) Virtual and erect**

**8. The SI unit of power of a lens is:**

(A) Meter

(B) Watt

(C) Diopter

(D) Hertz

**Answer: (C) Diopter**

**9. Resistance of a conductor is inversely proportional to its:**

(A) Length

(B) Area of cross-section

(C) Temperature

(D) Material density

**Answer: (B) Area of cross-section**

**10. What defect of vision occurs when an individual cannot see nearby objects clearly?**

(A) Myopia (Short-sightedness)

(B) Hypermetropia (Long-sightedness)

(C) Presbyopia

(D) Astigmatism

**Answer: (B) Hypermetropia (Long-sightedness)**

**11. Commercial unit of electric energy (1\text{ kWh}) is equal to:**

(A) 3.6 \times 10^6\text{ J}

(B) 3.6 \times 10^5\text{ J}

(C) 1000\text{ J}

(D) 360\text{ J}

**Answer: (A) 3.6 \times 10^6\text{ J}**

**12. The magnetic field lines inside a current-carrying solenoid are:**

(A) Circular

(B) Parabolic

(C) Parallel straight lines

(D) Elliptical

**Answer: (C) Parallel straight lines**

**13. A device that converts mechanical energy into electrical energy is a:**

(A) Electric motor

(B) Electric generator

(C) Transformer

(D) Galvanometer

**Answer: (B) Electric generator**

**14. In Fleming's Left-Hand Rule, the forefinger indicates the direction of:**

(A) Electric current

(B) Magnetic field

(C) Motion/Force on the conductor

(D) Induced current

**Answer: (B) Magnetic field**

**15. Blue color of the sky is due to:**

(A) Refraction of light

(B) Dispersion of light

(C) Scattering of light

(D) Atmospheric reflection

**Answer: (C) Scattering of light**

10 वीं के फिजिक्स के ऑब्जेक्टिव प्रश्न।

### **बिहार बोर्ड कक्षा 10 भौतिकी - 20 अति महत्वपूर्ण प्रश्नोत्तर**

**1. वाहनों के पश्च-दृश्य (rear-view) दर्पण के रूप में किस दर्पण का उपयोग किया जाता है?**

(A) अवतल दर्पण

(B) उत्तल दर्पण

(C) समतल दर्पण

(D) इनमें से कोई नहीं

**उत्तर: (B) उत्तल दर्पण**

**2. दाढ़ी बनाने (हजामत) के लिए किस दर्पण का उपयोग किया जाता है?**

(A) समतल दर्पण

(B) उत्तल दर्पण

(C) अवतल दर्पण

(D) द्विफोकसी दर्पण

**उत्तर: (C) अवतल दर्पण**

**3. प्रकाश के अपवर्तन के कितने नियम हैं?**

(A) 1

(B) 2

(C) 3

(D) 4

**उत्तर: (B) 2**

**4. लेंस की क्षमता (Power of Lens) का S.I. मात्रक क्या होता है?**

(A) डायोप्टर (D)

(B) ल्यूमेन

(C) लक्स

(D) मीटर

**उत्तर: (A) डायोप्टर (D)**

**5. समतल दर्पण द्वारा बना प्रतिबिंब हमेशा कैसा होता है?**

(A) वास्तविक

(B) काल्पनिक (आभासी)

(C) दोनों

(D) इनमें से कोई नहीं

**उत्तर: (B) काल्पनिक (आभासी)**

**6. मानव नेत्र के लिए स्पष्ट दृष्टि की न्यूनतम दूरी कितनी होती है?**

(A) 25 m

(B) 25 cm

(C) 25 mm

(D) अनंत

**उत्तर: (B) 25 cm**

**7. निकट दृष्टि दोष को दूर करने के लिए किस लेंस का उपयोग किया जाता है?**

(A) उत्तल लेंस

(B) अवतल लेंस

(C) बेलनाकार लेंस

(D) बाइफोकल लेंस

**उत्तर: (B) अवतल लेंस**

**8. दूर दृष्टि दोष के निवारण के लिए किस लेंस का प्रयोग होता है?**

(A) अवतल लेंस

(B) उत्तल लेंस

(C) समतल लेंस

(D) बेलनाकार लेंस

**उत्तर: (B) उत्तल लेंस**

**9. श्वेत प्रकाश जब प्रिज्म से गुजरता है, तो किस रंग का विचलन सबसे अधिक होता है?**

(A) लाल

(B) पीला

(C) बैगनी

(D) हरा

**उत्तर: (C) बैगनी**

**10. स्पेक्ट्रम प्राप्त करने के लिए किसका उपयोग किया जाता है?**

(A) काँच की सिली

(B) अवतल दर्पण

(C) उत्तल लेंस

(D) प्रिज्म

**उत्तर: (D) प्रिज्म**

**11. विद्युत आवेश का S.I. मात्रक क्या है?**

(A) वोल्ट

(B) ओम

(C) कूलॉम

(D) एम्पियर

**उत्तर: (C) कूलॉम**

**12. परिपथ में विभवांतर मापने वाले यंत्र को क्या कहते हैं?**

(A) अमीटर

(B) वोल्टमीटर

(C) गैल्वेनोमीटर

(D) वोल्टामीटर

**उत्तर: (B) वोल्टमीटर**

**13. विद्युत धारा का S.I. मात्रक क्या होता है?**

(A) एम्पियर

(B) वोल्ट

(C) ओम

(D) वाट

**उत्तर: (A) एम्पियर**

**14. ओम के नियम में किसका मान अचर (नियतांक) रहता है?**

(A) धारा

(B) ताप

(C) विभवांतर

(D) प्रतिरोध

**उत्तर: (B) ताप**

**15. 1 किलोवाट-घंटा (1 kWh) किसके बराबर होता है?**

(A) 3.6 × 10⁶ J

(B) 3.6 × 10⁵ J

(C) 3.6 J

(D) 0.36 J

**उत्तर: (A) 3.6 × 10⁶ J**

**16. विद्युत फ्यूज विद्युत धारा के किस प्रभाव पर कार्य करता है?**

(A) ऊष्मीय प्रभाव

(B) चुंबकीय प्रभाव

(C) रासायनिक प्रभाव

(D) इनमें से कोई नहीं

**उत्तर: (A) ऊष्मीय प्रभाव**

**17. डायनेमो (जनरेटर) किस सिद्धांत पर कार्य करता है?**

(A) विद्युत चुंबकीय प्रेरण पर

(B) धारा के ऊष्मीय प्रभाव पर

(C) प्रेरित विद्युत पर

(D) इनमें से कोई नहीं

**उत्तर: (A) विद्युत चुंबकीय प्रेरण पर**

**18. फ्लेमिंग के वामहस्त (बाएँ हाथ) के नियम में अंगूठा किसकी दिशा दर्शाता है?**

(A) धारा की दिशा

(B) चुंबकीय क्षेत्र की दिशा

(C) बल की दिशा

(D) इनमें से कोई नहीं

**उत्तर: (C) बल की दिशा**

**19. सौर सेल सौर ऊर्जा को किस ऊर्जा में रूपांतरित करता है?**

(A) प्रकाश ऊर्जा

(B) गतिज ऊर्जा

(C) विद्युत ऊर्जा

(D) तापीय ऊर्जा

**उत्तर: (C) विद्युत ऊर्जा**

**20. बायोगैस (गोबर गैस) का मुख्य घटक कौन-सा है?**

(A) मीथेन (CH₄)

(B) एथेन

(C) प्रोपेन

(D) ब्यूटेन

**उत्तर: (A) मीथेन (CH₄)**