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CURRENT ELECTRICITY
~Sparsha Sreeharsha
Multiple Choice Questions:-
1- The S.I. unit of charge is: a- Ampere b- Coulomb c- Ohm d- Volt 2- The charge on an electron is: a- +1.6 X 10-19^ C b- -1.6 X 10
- C c- +1.6 X 10^20 C d- -1.6 X 10
C 3- The number of electrons in 1 C charge is: a- 6.25 X 10 18 b- 6.25 X 10^19 c- 6.25 X 10 25 d- 1.6 X 10
4- The current in a circuit is measured by …………. By …………..connecting it in ………….. a- Voltmeter, series b- Voltmeter, parallel c- Ammeter, series d- Ammeter, parallel 5- If W joule of work is done in bringing test charge Q Coulomb from infinity to a point P, then electric potential V at point P is: a- V = W Q
b- V = Q/W c- V = W/ Q, d- none of the above 6- Potential at a point is said to be one volt, when …………… of work is done in bringing one coulomb of charge from infinity to a point a- 1 joule b- 5 joule c- 10 joule d- 1 erg 7- The potential difference between two points in an electric circuit is measured by a ……… which is connected in ………. With the circuit a- Voltmeter, series b- Voltmeter, parallel c- Ammeter, series d- Ammeter, parallel 8- The obstruction offered to a flow of current by a wire is called: a- Current b- Potential c- Resistance d- Charge 9- 1 ohm is equal to: a- 1volt b- Volt X ampere c- Volt/ Ampere d- All of the above 10- Electrical resistivity of a given metallic wire depends upon a- Its length b- Its thickness c- Its shape
15 - If the strength of the current flowing through a wire is increased, the strength of the magnetic field produced by it: (a) decreases (b) increases (c) remains the same (d) first increases then decreases
Answer the following:-
1- (i) What is an Ohmic resistor? (ii) Two copper wires are of same length, but one is thicker than the other. 1- Which wire will have more resistance?, 2- Which wire will have more specific resistance? 2- What happens to the resistivity of semi conductors with the increase in temperature? 3- The relationship between the potential difference and current in a conductor is stated in the form of a law. [2015] (i) Name the law (ii) What does the slope of the V-I graph for the conductor represent? (iii) Name the material used for the making of the connecting wire 4- (a) Define specific resistance (b) What happens to the specific resistance of a conductor if its length is doubled? (c) Name a substance whose specific resistance remains almost unchanged with the increase in temperature [2023]
5- The electrical gadgets used in a house such as bulbs, fans, heaters are always connected in parallel, not in series. Give two reasons for connecting them in parallel 6- Mention two factors on which the resistance of a wire depends 7- What is the effect of temperature on metals and semi- conductors? 8- (i) Draw a graph of potential difference (V) versus current (I) for an ohmic resistor (ii) How can you find the resistance of the resistor from this graph? (iii) What is a non-ohmic resistor? 9- Through a diagram illustrate how you would connect a key, a battery, a voltmeter, an ammeter, an unknown resistor R and a rheostat so that it can be used to verify the above law. 10 Explain the concept of potential difference taking the analogy of water flow. 11 – what do you mean by the terms:- (i) Potential (ii) Electromotive force (iii) Potential difference 12- State the factors that alter the resistance of a conductor
20- If three resistors R1, R2, and R3 are connected end to end across the terminals of a battery through a key, what will be the equivalent resistance of the combination? 21- You are given three resistors R1, R2, and R 3. If one end of each resistor is connected at one point (A) and the other end of each resistor is connected to the other point (B), and the battery is connected between these two points (A) and (B) through a key, obtain the expression for the equivalent resistance of the combination. 22- (a) Why is a coiled filament used in a bulb? (b) Why are thick wires used in the leads of an electric radiator? 23- (a) a cell is sending current in an external circuit. How does the terminal voltage compare with the e.m.f. of the cell? (b) How should the electric lamps in a building be connected? 24- Electric power is given by the expression: P = (Q X V) / time. (a)What do the symbols Q and V represent? (b)Express power in terms of current and resistance explaining the symbols used therein. [2023] 25- What is the heating effect of current? Explain the cause of heat produced in a conductor when current is passed through it.; State the factors on which the heat produced depends. [2012]
