Problem Sheet – II (based on UNIT – II)
· Following questions carry 1 mark each:-
1. Two wires of equal length, one copper and the other of magnanin, have the same resistance. Which wire is thicker?
2. Define conductivity of a material. Give its S.I. unit.
3. State Kirchoff’s Current Law.
4. Why potentiometer is preferred over voltmeter for measuring emf ?
5.
A copper wire of resistivity
is stretched to reduce its diameter to half its previous value. What will be its new resistivity?
· 2 marks questions:-
1. State Ohm’s Law. A 47 k ohms carbon resistor is to be marked with different coloured rings for its identification, write down the sequence of colours.
2. Apply Kirchoff’s Law to obtain the condition of balance in a Wheatstone Bridge.
3. Three identical cells, each of emf 2 V and internal resistance 0.2 ohms are connected in series to an external resistor of 7.4 ohm. Calculate the current in the circuit.
4. Two cells of emf V1 and V2 ( V1> V2) are connected as shown in the figure:
When a potentiometer is connected between the V1 and the middle point, the balncing length of the potentiometer is 300 cm. On connecting the same pot between two extreme ends is balance pt is at 100 cm. Calculate the ratio of V1 and V2.
5. State and explain Seebeck effect.
- State Faraday’s Laws of electrolysis. Derive the relation connecting chemical equivalent and electrochemical equivalent of an element.
- The p.d. across the terminals of a battery of emf 12V and internal resistance 2 ohms drops to 10V when it is connected to a silver voltameter. Calculate the silver deposited at the cathode in half an hour. At wt.107.9
- In the following network, show that the total power dissipation in the resistors is equal to the total power supplied by the sources:-
- Explain how a potentiometer can be used to measure the emf of an unknown battery.
