1. Two
wires of same material are having length L and 2L. Compare their resistance and
resistivity.
2. Why are coils of electric toaster and electric iron made of an alloy rather than a pure metal?
3. Two wires are of same length and radius but one of them is copper and the other is of iron. Which will have more resistance? (Given the resistivity of copper = 1.62 x 10 -8 ohm meter and resistivity of iron = 10 x 10-8 ohm meter.
4. Define 1KWh. Give the relation between 1kwh and Joule.
5. State which has a higher resistance. A 50W or 25W lamp. Also find the ratio of their resistances.
6. A wire of resistance 5 Ohm is spent in the form of closed circle. What is the resistance between 2 points at the ends of any diameter of the circle?
7. Calculate the amount of charge that would flow in one hour through the element of an electric iron drawing a current of 0.4 amps.
8. A electric toaster of resistance 20 Ohm takes a current of 5A. Calculate the heat developed in 30 s.
9. A bulb is rated at 5V, 100mA. Calculate its (1) Power (2) Resistance
10. Name two special characteristics of a heater coil.
2. Why are coils of electric toaster and electric iron made of an alloy rather than a pure metal?
3. Two wires are of same length and radius but one of them is copper and the other is of iron. Which will have more resistance? (Given the resistivity of copper = 1.62 x 10 -8 ohm meter and resistivity of iron = 10 x 10-8 ohm meter.
4. Define 1KWh. Give the relation between 1kwh and Joule.
5. State which has a higher resistance. A 50W or 25W lamp. Also find the ratio of their resistances.
6. A wire of resistance 5 Ohm is spent in the form of closed circle. What is the resistance between 2 points at the ends of any diameter of the circle?
7. Calculate the amount of charge that would flow in one hour through the element of an electric iron drawing a current of 0.4 amps.
8. A electric toaster of resistance 20 Ohm takes a current of 5A. Calculate the heat developed in 30 s.
9. A bulb is rated at 5V, 100mA. Calculate its (1) Power (2) Resistance
10. Name two special characteristics of a heater coil.
Short answer questions (3 marks)
1. Define resistance and resistivity. Give the relation between them. Explain the dependence of resistance on temperature.
2. With the help of neat circuit, derive the expression for the equivalent resistance of 3 resistances connected in series.
3. With the help of neat circuit, derive the expression for the equivalent resistance of 3 resistances connected in parallel
4. (a ) Draw the circuit consisting of a battery of five 2V cells, 5ohm resistor, 10 ohm resistor, 15 ohm resistor and a plug key. All connected in series (b) calculate the current passing through the above circuit when key is closed.
1. Define resistance and resistivity. Give the relation between them. Explain the dependence of resistance on temperature.
2. With the help of neat circuit, derive the expression for the equivalent resistance of 3 resistances connected in series.
3. With the help of neat circuit, derive the expression for the equivalent resistance of 3 resistances connected in parallel
4. (a ) Draw the circuit consisting of a battery of five 2V cells, 5ohm resistor, 10 ohm resistor, 15 ohm resistor and a plug key. All connected in series (b) calculate the current passing through the above circuit when key is closed.
5. Two
identical resistors each of resistance 2 Ohm are connected in turn
(1) in series (2) in parallel
to a battery of 12 V. Calculate the ratio of power consumed in two cases.
6. A piece of wire is redrawn by pulling it until its length is tripled. Compare the new resistance with the original value.
7. An electric kettle is rated 500W, 200V. IT is used to heat 400 gm of water for 30 secs. Assuming the voltage to be 220V calculate the rise in temperature of water. Specific heat capacity of water is 4200 J/Kg ºC.
8. What is the resistance of a copper wire 20 meters long and 0.81 mm in diameter at 20°?
6. A piece of wire is redrawn by pulling it until its length is tripled. Compare the new resistance with the original value.
7. An electric kettle is rated 500W, 200V. IT is used to heat 400 gm of water for 30 secs. Assuming the voltage to be 220V calculate the rise in temperature of water. Specific heat capacity of water is 4200 J/Kg ºC.
8. What is the resistance of a copper wire 20 meters long and 0.81 mm in diameter at 20°?
9. A heater
draws 1100 W at 220V. (a) Find the resistance of the heater (b) Calculate the energy in KWh consumed in a week if the
heater is used daily for 4 hours.
10. The
following three appliances are connected in series to a 120 V house circuit: a
toaster, 1200 W; a coffee pot, 750 W;
and a microwave, 6.0 × 102 W. If all were operated at the same time, what total
current would they draw?
11. Three
resistors with values of 3.0 Ω, 6.0 Ω, and 12 Ω are connected in series. What
is the equivalent resistance
of this combination?
12. Three
resistors with values of 4.0 Ω, 6.0 Ω, and 10.0 Ω are connected in parallel.
What is their equivalent
resistance?
13. Two
resistors with values of 6.0 Ω and 12 Ω are connected in parallel. This
combination is connected in
series with a 4.0 Ω resistor. What is the overall resistance of this combination?
14. A circuit
contains a 1.5 volt battery and a bulb with a resistance of 3 ohms. Calculate
the current.
15. Two
resistors with values of 6.0 Ω and 12 Ω are connected in parallel. This
combination is connected in
Series with a 2.0 Ω resistor and a 24 V battery. What is the current in the 2.0 Ω resistor?
16. What is
the equivalent resistance for the resistors in the figure below?
17. What is the equivalent resistance for the resistors in the figure below?
18. For the circuit shown below find the following,
17. What is the equivalent resistance for the resistors in the figure below?
18. For the circuit shown below find the following,
a. What is the equivalent resistance for the resistors in
the figure below?
b. What is the total voltage drop across the entire below
circuit?
1. State Ohms law with a neat circuit. Explain how this law can be verified and also plot the expected v-I graph.
2. (a) Differentiate resistance and resistivity
(b) the ratio of resistivities of two materials a and b is 1:2, ratio of their length is 3:4 and if the ratio of radii is 2:3 find the ratio of resistance of a and b.
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