Physics Questions and Answers

1.

Two electric bulbs marked 25W – 220V and 100W – 220V are connected in series to a 440Vsupply. Which of the bulbs will fuse?

   A.) 100 W
   B.) 25 W
   C.) Both
   D.) Neither

Answer: Option 'B'

Resistances of both the bulbs are

R1=V^2/P1 = 220^2/25

R2 = V^2/P2 = 220^2/100

Hence  R1gt ; R2R1gt ; R2

When connected in series, the voltages divide in them in the ratio of their resistances. The voltage of 440 V devides in such a way that voltage across 25 w bulb will be more than 220 V. Hence 25 w bulb will fuse.

2.

It is more difficult to walk on ice than on a concrete road because

   A.) there is more friction between the ice and feer
   B.) there is very little friction between the ice and feet pressing it
   C.) ice is soft when compared to concrete
   D.) None of these

Answer: Option 'B'

It is the friction between the feet and the ground that helps us to walk. Without this friction we would slip and fall

3.

Which of the following is not a vector quantity

   A.) speed
   B.) velocity
   C.) torque
   D.) displacement

Answer: Option 'A'

speed

4.

The working principle of a washing machine is

   A.) centrifugation
   B.) diffusion
   C.) reverse osmosis
   D.) dialysis

Answer: Option 'A'

centrifugation

5.

Nuclear sizes are expressed in a unit named

   A.) Newton
   B.) Fermi
   C.) Angstrom
   D.) Tesla

Answer: Option 'B'

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.

6.

The speed of light will be minimum while passing through

   A.) air
   B.) water
   C.) vaccum
   D.) glass

Answer: Option 'D'

glass

7.

It is more difficult to walk on ice than on a concrete road because 

   A.) there is very little friction between the ice and feet pressing it
   B.) ice is soft when compared to concrete
   C.) there is more friction between the ice and feer
   D.) None of these

Answer: Option 'A'

there is very little friction between the ice and feet pressing it

8.

A solid ball of metal has a spherical cavity inside it. When the ball is heated the volume of the cavity will

   A.) remain unaffected
   B.) increase
   C.) decrease
   D.) have its shape changed

Answer: Option 'B'

The metal ball can be considered  to be made up of several layers of thinner ones. On heating each of these layers will increase in radius. As the inner most layer also increases its radius, the volume inside it i.e, the volume of the hollow portion will also increase.

9.

If a sound travels from air to water, the quantity that remain unchanged is

   A.) wavelength
   B.) velocity
   C.) amplitude
   D.) frequency

Answer: Option 'D'

frequency

10.

When a bottle of perfume is opened in one corner of a room the smell spreads soon throughout the room. This is an example of

   A.) viscosity
   B.) diffusion
   C.) capillarity
   D.) surface tension

Answer: Option 'B'

diffusion
Diffusion is the spreading  - mixing of gases through molecular motion.


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