Very Short Answers (1 Mark)
1. Define the SI unit of (one mark each)
(a) Current
(b) Potential Difference
(c) Resistance
(d) Electric Power
(e) Electric Energy (Commercial)
2. What is the conventional direction of flow of current?
3. Define the term resistivity?
4. On what factors does the resistance of a conductor depend?
5. How is the voltmeter and ammeter connected in the electric circuit?
6. Heating effect of current carrying conductor is due to –
(Ans : loss of kinetic energy of electron)
7. Why the filament of bulb has high melting point?
8. How does use of a fuse wire protect electrical appliance?
9. What is the relationship between power, current and potential difference
(Ans : P = VI)
10. How many joules are there in 1KWh?
Short Answer (2-3 marks) type Questions
1. Draw a schematic diagram of a circuit consisting of a battery of six cell of 1.5V each, three resistor each of 3Ω in series and a plug key.
2. State Ohm’s law. Draw the graph between V&I?
3. What is joule’s heating effect of current, derive its expression?
4. A wire of length L and R is stretched so that its length’s doubled and the area of cross section is halved. How will its
(i) Resistance change
(ii) Resistivity change.
Q.1: Observe the given circuit diagram carefully and answer the questions that follow:
1. What are the currents drawn by the least and the highest of the three resistors?
2. What is the current drawn by the 6 Ω resistor?
3. What would be the reading of the ammeter?
4. How much current does the least of the three resistors, draw from the given battery?
5. Is the equivalent resistance of the parallel combination shown, more or less than the least (= 4 – 2) Ω, of the individual resistances?
Q.2: Read the given information carefully and answer the questions that follow:
(1) The resistivity of copper is less than that of aluminum which, in turn is less than that of constantan.
(2) There are nine wires, labeled as A, B, C, D, E, F, G, H, I, that have been designed as per the tabular details given below:
Answer the following questions:
1. Arrange the three values R1, R2, R3 in increasing order.
2. Arrange the three values R7, R8, R9 in decreasing order.
3. Which of the two has a lower value?
(i) R4 and R6
(ii) R1 and R8
4. Will the graph between R1, R2, R3 (on the y-axis) and their corresponding length values (on the x-axis) be a straight line?
5. What is the likely value of the ratio R4/R6?
Q.3: An electric geyser is known to consume 2.2 ‘units’ of electrical energy per hour of its use. It is designed to work on the mains voltage of 220V.
1) What is the ‘power-rating’ of this device?
2) What is the current flowing through this device when it is connected across the ‘mains’?
3) What is the ‘resistance’ of this device?
4) Does the resistance of this device remain constant during its operation/working?
5) Which of the two- a 100W, 220V lamp, or a 10W, 220V night lamp – has a higher resistance?
Q.4: Observe the given circuit carefully and answer the questions that follow:
1. What is the total equivalent resistance of the circuit?
2. What would be the reading of the ammeter?
3. What would be the reading of a voltmeter connected between the points Q and R?
4. What would be the reading of the ammeter if only the highest of the three resistors (= 5Ω) were present alone in the circuit?
5. What would be the reading of a voltmeter connected between the points P and S?
Q.5: Dear students are you aware of these following terms which are related to Electricity, proper and safe use of electricity, and basic safety precautions (if yes that’s good, otherwise asks your subject teacher):
1. What are the basic safety precautions?
1. What are the Current rating, voltage rating, frequency rating, power rating of electric appliances?
2. The importance of ‘earthing’ the metallic bodies of electrical appliances.
3. Why we using ‘fuse wires’/MCB’s of the correct rating.
4. We should use ‘electricity as a good servant’ and not let it become ‘a bad master’.
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