Physics Questions

Q:

The working principle of a washing machine is

A) reverse osmosis B) diffusion
C) centrifugation D) dialysis
 
Answer & Explanation Answer: C) centrifugation

Explanation:

The working principle of a washing machine is centrifugation.

 

The_working_principle_of_a_washing_machine_is1542349278.jpg image

 

Centrifugation is a separation process which uses the action of centrifugal force to promote accelerated settling of particles in a solid-liquid mixture.

The washing machine consists of centrifuge for this purpose. A centrifuge is a piece of equipment that puts an object in rotation around a fixed axis, applying a force perpendicular to the axis of spin that can be very strong.

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Q:

Nuclear sizes are expressed in a unit named

A) Fermi B) Angstrom
C) Newton D) Tesla
 
Answer & Explanation Answer: A) Fermi

Explanation:

Nuclear sizes are expressed in a unit called "Fermi" which is a unit of length equal to 10−15 metre (one femtometre), used in nuclear physics. It is similar to the diameter of a proton.

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Q:

The speed of light will be minimum while passing through

A) water B) vaccum
C) air D) glass
 
Answer & Explanation Answer: D) glass

Explanation:
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Q:

Which of the following is not a vector quantity?

A) speed B) velocity
C) torque D) displacement
 
Answer & Explanation Answer: A) speed

Explanation:

Which_of_the_following_is_not_a_vector_quantity1552385336.png image

A vector quantity is a quantity which has both magnitude and direction. Here in the given options, speed is a scalar quantity but not the vector quantity.

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Q:

The most suitable unit for expressing nuclear radius is

A) micro B) nanometre
C) fermi D) angstrom
 
Answer & Explanation Answer: C) fermi

Explanation:
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Q:

Which of the following is not the unit of time

A) Parallactic second B) Micro Second
C) Leap year D) Solar day
 
Answer & Explanation Answer: A) Parallactic second

Explanation:
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Q:

The purpose of choke in tube light is

A) Induce high voltage B) Induce low resistance
C) Induce high resistance D) Induce low voltage
 
Answer & Explanation Answer: A) Induce high voltage

Explanation:

When the switch is ON, in a tube light choke is nothing but the coil/ballast ( inductor) which is used to induce the high voltage across it. as we know that inductor has property to induce high voltage for the brief period of time, this high voltage is required to ionize the gases in the starter.

Then gas inside the starter gets ionized due to this full voltage and heats the bimetallic strip that is caused to be bent to connect to the fixed contact. Current starts flowing through the starter. Although the ionization potential of the neon is the little bit more than that of the argon but still due to small electrode gap high voltage gradient is appeared in the neon bulb and hence glow discharge is started first in a starter.

As voltage gets reduced due to the current causes a voltage drop across the inductor, the strip cools and breaks away from the fixed contact. At that moment a large L di/dt voltage surge comes across the inductor at the time of breaking.

This high valued surge comes across the tube light electrodes and strikes penning mixture (mixture argon gas and mercury vapor).

Gas discharge process continues and current gets the path to flow through the tube light gas only due to low resistance as compared to the resistance of starter.

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Q:

An air bubble in water will act like a

A) convex lens B) convex mirror
C) concave lens D) concave mirror
 
Answer & Explanation Answer: C) concave lens

Explanation:

An_air_bubble_in_water_will_act_like_a1557488532.jpg image

The lens which have atleast one inward curved surface is a concave lens. Concave ens is a diverging lens as it spreads out light rays that have been refracted through it.

A concave lens is thinner at its centre than at its edges.

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