set 8 MCQ Questions & Answers Detailed Explanation

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The following question based on light, heat, thermodynamics, wave motion, sound, optics & oscillations topic of general science mcq

Questions : A solid cube and a solid sphere of the same material have equal surface area. Both are at the same temperture 120°C , then

(a) the sphere cools down faster than the cube

(b) both the cube and the sphere cool down at the same rate

(c) the cube cools down faster than the sphere

(d) whichever is having more mass will cool down faster

The correct answers to the above question in:

Answer: (c)

Rate of cooling of a body R = ${Δϴ}/t = {Aɛσ(T^4 - {T_O}^4)}/{mc}$

⇒ $R ∝ A/m ∝ \text"Area"/\text"Volume"[m = ρ×V]$

⇒ For the same surface area. $R ∝ 1/\text"Volume"$

Since Volume of cube < Volume of a sphere

⇒ $R_{cube} > R_{Sphere}$

i.e., the cube cools down at a faster rate.

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Read more light heat thermodynamics wave sound optics oscillation Based General Science Questions and Answers

Question : 1

At a given temperature the internal energy of a substance

a) in liquid state is more than that in gaseous state

b) in liquid state is equal to that in gaseous state

c) in liquid state is less than that in gaseous state

d) is equal for the three states of matter

Answer: (c)

Question : 2

The wavelength of radiation emitted by a body depends upon

a) the temperature of its surface

b) the nature of its surface

c) the area of its surface

d) All of the above

Answer: (d)

Question : 3

The normal temperature of human body is 98.4°F. It’s equivalent temperature (in °C) is

a) 36.89

b) 35.72

c) 40.16

d) 32.36

Answer: (a)

Question : 4

The power of a lens is measured in

a) Lumen

b) Aeon

c) Dioptre

d) Candela

Answer: (c)

Question : 5

A cut diamond shines brilliantly due to

a) Some inherent property

b) Absorption of light

c) Total internal reflection

d) Its molecular structure

Answer: (c)

Question : 6

Sound waves

a) can travel only in solid

b) can travel only in gases

c) can travel in vacuum

d) can travel both in solid and gaseous medium

Answer: (d)

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