iGCSE Physics (0625)-Unit 4. Electricity and magnetism-4.2.3 Electromotive force- Paper 4

iGSCE Physics Paper 4 - All Chapters

Question

(a) Define electromotive force (e.m.f.).                    [1]

(b)Fig. 8.1 shows a source E of e.m.f. 60 V in a circuit.

                                       

The heater H has a resistance of 22.5 Ω and the potential difference (p.d.) across it is 45 V. Calculate:

    1. the power of the heater

        power = ……………………………………………………       [3]

    2. the p.d. across resistor X

       p.d. = ……………………………………………………         [2]

    3. the current in the 10 Ω resistor.

            current = ………………………………………………………………     [2]

                                                                                                                                                                                                       [Total: 8]

    Answer/Explanation

    Ans:

    (a)energy supplied by a source in driving charge around a complete circuit / energy needed to drive unit charge / 1 coulomb round circuit

    (b)(i)

    P=90 W

    P=V I 

    V / R

    OR

    I = 2

    (b)(ii)

    p.d. = 15 V

    p.d. = 60 –45

    b(iii)

    I = 15 / 10 = 1.5 

    I =V / R

    OR V = I R 

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