21. An image formed by a plane mirror will always be.
Answer: Virtual and erect
22. The ratio of the sine of the angle of incidence to the sine of the angle of refraction for a given pair of media is always constant. This rule is called _____.
Answer: Snell’s law
23. Which of the following will have a higher refractive index?
Answer: Diamond
24. The effective diameter of the circular outline of a spherical lens is called _____.
Answer: Aperture
25. The SI unit of a lens’s power is
Answer: Diopter
26. The AC supply in a house is 220 V, 50 Hz, one wire in this supply is red, which is called _____.
Answer: Ground wire
27. During electric shock, the electric current in the circuit
Answer: Increases significantly
28. The safety device used to protect circuits from electric shock is
Answer: Fuse
29. A 2 kW electric oven rated for 220 V is operated on a household electric current. The current taken by the oven is:
Answer: 9.09 A
30. The focal length of a plane mirror is:
Answer: Infinite
31. An electric current flows horizontally from east to west. The direction of the magnetic field at a point directly below the power line is:
Answer: South to North
32. The magnetic field of a long straight conductor carrying current:
Answer: Is the same at all points
33. According to Fleming’s Left Hand Rule, the direction indicated by the forefinger is:
Answer: Magnetic field
34. The device that can detect the presence of electric current in a circuit is:
Answer: Galvanometer
35. The fundamental phenomenon in the operation of an electric generator is:
Answer: Electromagnetic induction
36. The minimum distance for distant vision for a person with normal vision is:
Answer: 25 cm
37. The change in the focal length of a lens is caused by the activity of:
Answer: Ciliary muscles
38. The electrical resistance of a given metallic wire depends on:
Answer: Nature of the material
39. The energy of a photon is related as follows:
Answer: E = hv
40. A soft iron rod is placed in an electric field. The magnetic field in the field:
Answer: Increases