41: If the length of a metallic wire is doubled, then the resistance of the wire
Answer: will be doubled
42: Which of the following will not be attracted by a magnet?
Answer: Brass
43: The radius of curvature of a convex mirror is 32 cm. Its focal length is
Answer: 16 cm
44: Which of the following materials cannot be used to make a lens?
Answer: Clay
45: Name the mirror used in a solar furnace.
Answer: Concave
46: A 2 cm tall object is placed perpendicular to the principal axis of a convex lens of focal length 10 cm. The object distance from the lens is 15 cm. The image distance is
Answer: 30 cm
47: The retina of the eye is a ________.
Answer: Light-sensitive layer
48: The reason for the twinkling of stars is
Answer: Atmospheric refraction
49: A person requires a lens with a power of -5.5 D to correct his myopia. What is the focal length of the desired lens for correcting myopia?
Answer: -0.181 m
50: The potential difference between two points is
Answer: Work done / Charge
51: A boy with a mass of 50 kg is standing on the ground, and a force of 500 N acts on him. The force exerted on the boy by the ground is
Answer: 500 Newton
52: The acceleration produced in a 20 kg object by a force of 5 N will be in m/s²
Answer: 0.25
53: According to Kepler’s laws of planetary motion
Answer: r³ ∝ T²
54: The weight of an object at the center of the Earth with radius R is
Answer: Zero
55: Which of the following is not a unit of energy?
Answer: Kilowatt
56: How much energy does a 100 W bulb convert in 1 minute?
Answer: 6000 Joules
57: When an object falls freely to the Earth, its total energy
Answer: Remains constant
58: In sonar, we use
Answer: Ultrasonic waves
59: What type of sound is produced during an earthquake?
Answer: Infrasound
60: Among the following, who can hear infrasound?
Answer: Dog