Energy

Q.

How does the fan work when i switch it on

Q.

Is solar cell forward biased?

Q.

Write the energy transformation that takes place in the following:

Television

Q.

State energy conversion that takes place during working of Microphone.

Q.

What are the properties of solar cells?

Q.

How many joules are there in $1$ kilowatt hour?

Q.

Give one example where heat energy can be converted to other forms of energy.

Q.

Energy is the ability of doing work.

1. True

2. False

Q.

When you compress a coil spring you do work on it. The elastic potential energy

1. increases

2. decreases

3. disappears

4. remains unchanged.

Q. A body of mass $2kg$ is dropped from a height of $1m$. Its kinetic energy as it touches the ground is (assume $g=9.8m{s}^{-2}$)

1. $19.6$ $N$
2. $19.6$ $J$
3. $19.6$ $kg$
4. $19.6$ $m$

Q.

An iron block of mass $2kg$ falls from a height of $10m$ after colliding with the ground it loses$25\%$ of energy to the surrounding then find the temperature rise of the block(take specific heat of $Fe=470J/Kg°C$)

Q.

An aeroplane flying high in the sky possesses :

1. Potential Energy

2. Kinetic Energy

3. both (A) and (B)

4. None of the above

Q.

What happens If we heat iron rod? Is it observable or not

Q.

Please explain in detail the motion in Roller Coaster Ride.

Q.

Hydro energy is an indirect source of solar energy. Justify this statement.

Q. 1 calorie = joules (J)

1. 4.2
2. 3.6
3. 5.2

Q.

In a solar cell, light energy is converted to what?

Q.

Name the energy changes taking place when the following devices are used: Bunsen burner.

Q.

How is solar energy directly converted into electrical energy?

Q.

Define the term ‘energy’. write the names of different forms of energy.

Q.

A body is kept in rest at some height and its kinetic energy is zero.

1. False

2. True

Q. A boy, his mother and father have their masses in the respective ratio 1:2:3. Find the ratio of their speeds at which they should run so as to have the same kinetic energy for each of them with respect to ground?

Q.

The energy used by a horse to pull cart is called

1. potential energy

2. Sound energy

3. Muscular energy

Q. What is Bernoulli effect?

Q.

Define the term calorie. How is it related to joule?

1. The amount of energy required to raise the temperature of 1 gram of water by 1 degree celsius, 1 cal = 4.18 J

2. The amount of energy required to raise the temperature of 1 gram of water by 1 kelvin, 4.18 Cal = 1 J

3. The amount of energy required to raise the temperature of 1 gram of water by 1 Fahrenheit, 4.18 Cal = 1 J

4. The amount of energy required to raise the temperature of 1 gram of ether by 1 degree celsius, 1 cal = 4.18 J

Q. Heating effect of current and its relations and application

Q.

State the energy change in the case of ceiling fans.

Q. A body rolling down a hill has

1. K.E. only
2. neither K.E. nor P.E.
3. both P.E. and K.E.
4. P.E. only

Q.

A machine does a work of $25kJ$ in $3minutes$ and $20seconds$. Calculate the power of the machine in $kW$.

Q.

A machine does a work of $1960J$ in $240s$. What is the power of the machine?