Electric Bell

Q.

How is the working of an electric bell affected, if alternating current be used instead of direct current?

Q. The polarity of an electromagnet can be changed by changing the direction of electric current through it.

1. False
2. True

Q.

Give one example, where electrical energy changes into sound energy.

Q.

Electric bell works on ___ effect of electric current.

1. magnetic

2. chemical

3. heating

4. heating and chemical

Q. Electric bell works on which of the following effects of current?

1. Heating effect
2. Magnetic effect
3. Chemical effect
4. Heating and chemical effect

Q.

Select the correct labelling of the following electric bell.

1. A – Striker, B- Contact Screw, C – Electromagnet, D - Gong

2. A – Gong, B- Contact Screw, C – Electromagnet, D - Striker

3. A – Striker, B- Electromagnet, C –Contact Screw, D - Gong

4. A – Striker, B- Gong, C – Contact Screw, D – Electromagnet

Q.

What is the principle of an electric bell?

1. Electrical energy is converted into sound energy

2. Mechanical energy is converted into sound energy

3. Electrical energy is converted into mechanical energy

4. Mechanical energy is converted into electrical energy

Q.

The incomplete diagram of an electric bell is given in the figure. Draw winding of coil on the core and complete the electric circuit in the diagram

Q.

The strength of an electromagnet depends on _______ and _______ flowing in the coil.

Q.

The material used for making the armature of an electric bell or a temporary electromagnet is

1. Soft iron, because it can be magnetised and demagnetised very easily

2. Steel, because it can be demagnetised very easily

3. Soft iron, because it can be magnetised with difficulty but demagnetised very easily

4. Steel, because it can be magnetised and demagnetised very easily

Q.

(a) What name is given to a cylindrical coil of diameter less than its length ?
(b) If a piece of soft iron is placed inside the coil mentioned in part (a) and current is passed in the coil from a battery, what name is then given to the device so obtained ?
(c) Give one use of the device mentioned in part (b).

Q. The polarity of an electromagnet can be changed by changing the direction of electric current through it.

1. False
2. True

Q. An electric bell uses the of current flowing through a conductor.

1. chemical effect
2. magnetic effect
3. thermal effect

Q.

Write a short note on an electromagnet.

Q.

Name the material used for making the armature of an electric bell. Give a reason for your answer.

Q. The polarity of an electromagnet can be changed by changing the direction of electric current through it.

1. False
2. True

Q. State whether true or false:

1. True
2. False

Q. How is the working of electric bell effected if ac current is used instead of dc current?

Q. Identify the part which receives electric current and causes the bell hammer to move and ring the bell:

1. 
2. 
3. 
4. 

Q.

Name one device that uses an electromagnet.