General Science Jkssb Physics Set 1 Mcqs (448 MCQs) | JKSSB & SSC Quiz

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jkssb physics set 1 mcqs

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Practice Questions

448 Total
Question 361 Discuss
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The working principle of an optical fiber is based on which of the following phenomena?

A
total internal reflection
B
diffraction of light
C
scattering of light
D
refraction with dispersion

Answer & Explanation

Correct Option: A

Optical fibers transmit light signals over long distances by trapping them inside the core through repeated total internal reflection.
Question 362 Discuss
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Two metallic spheres of the same mass are heated to the same temperature and then left in the same surroundings. If sphere X is painted black and sphere Y is polished, which of the following is true?

A
sphere y will cool faster
B
sphere x will cool faster
C
both will cool at the same rate
D
cooling depends on the density of the metal

Answer & Explanation

Correct Option: B

Black bodies are better emitters of radiation than polished surfaces, leading to a faster rate of cooling for sphere X.
Question 363 Discuss
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A liquid is kept in a thermos flask. If the flask is vigorously shaken, the temperature of the liquid will:

A
increase
B
decrease
C
remain the same
D
decrease then increase

Answer & Explanation

Correct Option: A

Shaking does work on the liquid, which is converted into internal thermal energy, thereby raising its temperature.
Question 364 Discuss
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Which physical quantity is conserved when a planet revolves around the Sun in an elliptical orbit?

A
linear speed
B
kinetic energy
C
angular momentum
D
linear momentum

Answer & Explanation

Correct Option: C

Since the gravitational force is a central force, the net torque is zero, leading to the conservation of angular momentum.
Question 365 Discuss
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The focal length of a convex lens is 25 cm. Its power in diopters is:

A
+4
B
-4
C
+0.04
D
-0.04

Answer & Explanation

Correct Option: A

Power $P = 1/f$ (in meters). $f = 0.25$ m, so $P = 1/0.25 = +4$ diopters.
Question 366 Discuss
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A balloon filled with helium rises in the air because:

A
air exerts an upward force on the balloon
B
the density of helium is less than the density of air
C
helium is a noble gas
D
the weight of the balloon is less than the buoyant force

Answer & Explanation

Correct Option: D

According to Archimedes' principle, an object rises when the upward buoyant force (weight of displaced air) is greater than its own weight.
Question 367 Discuss
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A fuse wire used in electrical circuits is made of an alloy that has:

A
high resistance and high melting point
B
low resistance and low melting point
C
high resistance and low melting point
D
low resistance and high melting point

Answer & Explanation

Correct Option: C

High resistance ensures sufficient heat production during a surge, while a low melting point allows the wire to break the circuit safely.
Question 368 Discuss
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The recoil of a gun after firing a bullet is a direct application of:

A
newtons first law of motion
B
conservation of angular momentum
C
newtons third law of motion
D
the law of inertia

Answer & Explanation

Correct Option: C

For every action (bullet moving forward), there is an equal and opposite reaction (gun moving backward), as per Newton's Third Law.
Question 369 Discuss
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A transformer is used to:

A
convert dc to ac
B
convert ac to dc
C
step up or step down dc voltage
D
step up or step down ac voltage

Answer & Explanation

Correct Option: D

Transformers work on electromagnetic induction, which requires a changing magnetic field provided only by Alternating Current (AC).
Question 370 Discuss
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The sky appears blue because of the:

A
scattering of light by dust and air molecules
B
reflection of light by the ocean
C
refraction of light by the atmosphere
D
dispersion of light through water droplets

Answer & Explanation

Correct Option: A

Rayleigh scattering states that shorter wavelengths (blue/violet) are scattered much more efficiently by atmospheric particles than longer wavelengths.
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