Qn 1. It is said that a fuse wire of proper amperage should be used in an electrical circuit . why

Qn 2. An electric heater of resistance 230? is connected to 230V supply. Calculate the heat energy produced by it in 1 second.

Qn 3. Analyse the given circuit diagram and answer the following questions. 1. What will be the electric current through the resistance A ? 2. What will be the electric current through the resistance B ? 3. What will be the ammeter reading? 4. How should be the resistance wire be arranged to reduce the ammeter reading ?

Qn 4. Nichrome is not used as filament in filament lamps. Why ?

Qn 5. Ajith says that if we use tungsten as heating coil we will get light energy as well as heat energy. What is your response to his statement ?

Qn 6.

A filament Lamp designed to work at a potential difference 250V has power 100W. What will be the power of this lamp when connected to a 100V supply?

Qn 7.

A heating coil of 10000? resistance works in 250V supply.

1. What is the current flowing in it ?
2. What is the power of heater ?
3. Will there be any difference in the temperature, If we reduce the length of the heating coil ? Why?

Qn 8.

Nowadays LED Lamps are widely used .

1. Name any two parts of this lamp & write the working of it.
2. Name any two instruments/tools used in the making of LED Lamp.

Qn 9.

A,B,C,D & E are five 10Ω resistors connected in a circuit as in the given diagram.

1. Calculate the effective resistance of the circuit.
2. What is the electric current through the circuit.

Qn 10.

Resistance of a 20cm long conductor is 20?. The conductor is bent into circular loops and connected in the circuit as in the given diagrams, Calculate the resultant resistance in each case.

Qn 11.

Power of a bulb which works in 220V is 100W. When the voltage in the circuit decreases the power becomes 25W, What will be the voltage at that time?

Qn 12.

Match the following related to LED Lamp

Qn 13.

LED Lamps save energy & are ecofriendly. Justify this statement

Qn 14.

Calculate the amount of heat energy produced when 1A current flows through a 1? resistance wire for 1 hour.   

Qn 15.

• Calculate the highest resistance that can be made  by using five 1Ω resistors ?   
• What is the lowest resistance  made by the same five 1Ω resistors. ?      
• Draw a circuit in which these resistance are arranged inorder to get the effective resistance = 3 1/2 Ω

Qn 16.

 

Qn 17.

An electrical device of power 440W  is connected to  230V power supply. Which among the following is the amperage of fuse to be used in this circuit ?

(a) 0.5A  (b) 2A  (c) 1.5A  (d) 4A

Qn 18.

1. When the switch is on, calculate the current in the circuit.
2. What is the purpose of fuse in a circuit ? 
3. What is the amperage of the fuse wire that can be used in this circuit?

Qn 19.

The given experiment is based on heating effect of electric current

1. Which device is used  to change the intensity of current in the circuit
2. Nichrome  is used to make the heating coil to change the temperature of water.Why do we use this  material as heating element? 
3. If we double the length of the coil immersed in water, what will be the change in the heat energy produced ?

Qn 20.

1. Name any to electrical heating devices.
2. Name the constituent metal  in the alloy used to make the heating coil of a heating appliance.
3. Calculate the heat energy produced when 1A current flows through 100Ω resistance wire for 1hour.  

Qn 21.

Aluminium and Nichrome wires of same length and thickness are used in the given circuit.

1. In which circuit the current through Aluminium and Nichrome  are  the same?
2. In which circuit, Nichrome wire gets heated more. Explain.  

Qn 22.

Analyse the diagram and answer the following questions.

1. How is Rheostat and resistor connected in this circuit?
2. If the Rheostat offers a Resistance of 50Ω, what is the current in the circuit 

Qn 23.

If a bulb  labelled as 100W/230V is connected to 115V power supply, What will be its Power ?                                                                                                                  (100W,25W, 12.5W, 50W)  

Qn 24.

Observe the given circuit Diagram. B1 is a torch bulb and B2 is an ordinary incandescent bulb.

1. Among B1  and B2 Which which one have higher resistance ?
2. If we switch on the circuit as arranged in diagram, Whether both the the bulbs will glow or not glow
3. What happens if we switch on the circuit after replacing B2 with another B1. Explain

Qn 25.

1. Write two disadvantages of incandescent lamps?
2. What is the arrangement/facility provided to increase the life of such bulbs.
3. How does the oxidation of filament reduced in such lamps?