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)*
