The part of the eye that controls the amount of light entering is MCQ with Answer and Explanation

The part of the eye that controls the amount of light entering is
A. Cornea
B. Lens
C. Iris
D. Retina
Answer: Option C
Solution (By JKSSB Mock Tests)
Iris adjusts pupil size.

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Practice More Physics Questions

Question #1
The instrument that measures atmospheric pressure is
A. Manometer
B. Barometer
C. Hydrometer
D. Lactometer

Correct Answer: Option B


Explanation:
Barometer measures atmospheric pressure. Mercury barometer (Torricelli) standard. Aneroid barometer. Manometer measures pressure difference. Hydrometer density. Lactometer milk purity.

This question belongs to: Science Physics
Question #2
A body of mass 5 kg moving with velocity 2 m/s collides with a stationary body of mass 3 kg and sticks to it. Combined velocity is
A. 0.8 m/s
B. 1.25 m/s
C. 5 m/s
D. 2 m/s

Correct Answer: Option B


Explanation:
Momentum before = 5×2=10, after = (5+3)v => v=10/8=1.25 m/s.

This question belongs to: Science Physics
Question #3
An AC generator produces alternating current. To convert an AC generator into a DC generator, which crucial component must be replaced?
A. The magnetic poles must be swapped.
B. The armature coil must be made of aluminum.
C. The split-ring commutator must be replaced with slip rings.
D. The slip rings must be replaced with a split-ring commutator.

Correct Answer: Option D


Explanation:
An AC generator uses continuous 'slip rings' which allow the output polarity to reverse every half-rotation of the coil, generating alternating current. To produce direct current (DC), the slip rings must be replaced by a 'split-ring commutator'. This commutator reverses the connections to the external circuit at the exact moment the coil's current reverses, ensuring current flows in only one direction outside.

This question belongs to: Science Physics