Introduction to Heat

Q.

What is opened while clicking the camera?

Q.

Conduction takes place in solids only.

1. True
2. False

Q.

Why does conduction happen mainly in solids and is not frequent in liquids and gases?

Q.

Does thermal conduction occur in vacuum?

Q.

Conduction is the slowest in solids.

1. True
2. False

Q.

Why does an icebox have double walls?

Q.

Why light follows a straight line path in air?

Q.

Why is the inside surface of the box of a pinhole camera is blackened?

Q. The SI unit used to measure temperature is:

1. Fahrenheit
2. Celcius
3. Joule
4. Kelvin

Q. Heat flows from _________ temperature to __________ temperature.

1. lower, lower
2. lower, higher
3. higher, higher
4. higher, lower

Q.

Write some advantages of a pinhole camera.

Q.

The clinical thermometer has graduations for a short range

1. $35°Cto42°C$

2. $0°Cto100°C$

3. $273Kto300K$

4. $30°Cto37°C$

Q.

On what principle do thermometer work?

Q.

Mercury thermometers are increasingly being replaced by digital thermometers. Which of the following is NOT a correct reason for this?

1. Digital thermometers are always more accurate than mercury thermometers

2. Digital thermometers are easier to read than mercury thermometers

3. Mercury is toxic

4. Mercury is difficult to dispose of in case it leaks

Q.

Solids get heated by ___________ only.

Q. The figure shows three opaque strips with very small holes of different shapes. Will the image of the sun obtained on the screen through these three holes be the same or different?

Q. Which of the following can never form a circular shadow?

Q.

A pinhole camera seems to be an Arabic invention of

1. 15th century

2. 11th century

3. 18th century

4. 20th century

Q.

Why is the inside surface of the box of a pinhole camera is blackened?

Q.

Define pinhole camera?

Q.

State whether the following statements are true or false. If false, rewrite the correct form of statements.

The kinetic energy of molecules of a substance increases with an increase in the temperature.

Q.

The time of exposure in a camera is controlled by a

1. shutter

2. convex lens

3. bellows

4. diaphram

Q.

Why does an ice box have double walls?

Q.

One day, Richa saw the shadow of a bird on the wall of her room. After some time, it disappears, and it surprised her where the bird has gone. Her brother explains it was nothing as it was the shadow of his hand.

Mention the values that Richas brother reflect?

Q.

Solids transfer heat by

1. conduction

2. convection

3. radiation

4. all the three

Q. Given below are four objects:

1. Boiling milk
2. Ice cream
3. Snow
4. Molten wax

Which of the objects given above is/are hot?

1. $1$ only
2. $1,2$ and $3$
3. $1$ and $4$
4. $3$ and $4$

Q.

When you rub your hands vigorously, your hands become hot. Why?

1. Rubbing of hands requires energy to be which is provided by heat energy

2. Hands become hot because of their size

3. Rubbing causes friction between the hands which in turn produces heat

4. Nothing actually happens