Assertion (A): Light year and astronomical unit both represent dimensions of length. Reason (R): Light year is the time taken by light to travel from the Sun to the Earth. MCQ with Answer and Explanation
Assertion (A): Light year and astronomical unit both represent dimensions of length. Reason (R): Light year is the time taken by light to travel from the Sun to the Earth.
A. A is true but R is false.
B. Both A and R are true but R is NOT the correct explanation of A.
C. A is false but R is true.
D. Both A and R are true and R is the correct explanation of A.
Answer: Option A
Solution (By JKSSB Mock Tests)
Assertion (A) is true because both light year and astronomical unit (AU) are units used to measure massive astronomical distances (lengths). Reason (R) is false because a light year is the distance light travels in a vacuum in one Earth year, not the time taken to travel from the Sun to Earth (which is about 8.3 minutes).
Explanation:
Power P = 1/f (in metre). f = 1/P = 1/2 = 0.5 m = 50 cm. Positive power indicates convex lens. For concave lens, power negative. Dioptre (D) is SI unit of power. Remember f in metres.
Explanation:
Joule's Law of Heating states that the heat (H) produced in a resistor is given by H = I²Rt. This indicates that the heat produced is directly proportional to the square of the electric current (I), directly proportional to the resistance (R), and directly proportional to the time (t) the current flows.
Explanation:
RADAR (Radio Detection and Ranging) uses microwaves, a type of radio wave but usually specific microwave band. Often answer is microwaves. But radio waves also correct. I'll specify microwave as typical answer. Could be radio. Better: microwave. Many exams say microwaves. I'll stick with B.
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