1. The focal length of a lens of capacity 4 dioptre is
(a) 0.25 m (b) 0.25 cm (c) 0.35 m (d) 0.35 cm
Ans:-(a)
2. Work done in the deflection of a magnet in a uniform magnetic field
(a) W=MB(1-sinθ) (b) W=MB sinθ (c)W=MB(1-cosθ) (d)W=MB cosθ
Ans:-(c)
3. Nature of electromagnetic waves is :
(a) transverse (b) longitudinal (c) both (a) & (b) (d) electrical
4. Which of the following is the cause of formation of rainbow ?
(a) Scattering (b) Diffraction (c) Dispersion (d) Refraction
5. Image formed on retina is :
(a) real and erect (b) real and inverted (c) virtual and erect (d) virtual and inverted
6. Ampere-hour is the unit of :
(a) power (b) charge (c) energy (d) potential difference
Ans:-(b)
7. Lenz's law is the result of which principle of conservation ?
(a) current (b) momentum (c) energy (d) charge
8.The source of solar energy is
(a) nuclear fission (b) chemical reaction (c) annihilation of elementry particles (d) nuclear fusion
9.which of the following is the best conductor of electricity ?
(a) silver (b) Copper (c) Gold (d) Zinc
10. The value of magnetic susceptibility of vacuum is
(a) equal to 0.5 (b) infinite (c) equal to one (d) zero
11. The value of angle of dip at magnetic pole of the earth is
(a) 0° (b) 90° (c) 45° (d) 180°
12. with the increase on temperature the resistivity of semiconductor
(a) Increases (b) Decreases (c) Remains constant (d) Becomes Zero
13. The resistance of ideal ammeter is
(a) Zero (b) Very small (c) Very large (d) infinite
14. The working of dynamo is based on the principle of
(a) Heating effect of current (b) Electro-magnetic induction (c) Induced magnetism (d) Induced electricity
15. A concave lens (n=1.5) is immersed in water (n=1.33), then it will behave as a
(a) Converging lens (b) Diverging lens (c) Prism (d) 1Concave mirror
16. When a body is charged,its mass
(a) Increases (b) Decreases (c) Remains constant (d) may increase or decrease
17. Optical fiber communication is based on which of the following phenomenon
(a) Total internal reflection (b) Scattering (c) Reflection (d) Interference
18. A convex lens is dipped in a liquid,whose refractive index is equal to refractive index of material of lens.Then its focal length will:
(a) become zero (b) become infinite (c) decrease (d) increase
19. The value of amplitude index is
(a) always 0 (b) between 1 and ∞ (c) between 0 and 1 (d) Always ∞
20. When a ray of light enters a glass slab,its wavelength
(a) increaes (b) decreases (c) remains unchanged (d) data are not complete
