10.1 The circuit below consists of a 6 Ω and 15 Ω resistor connected in parallel and an unknown resistor R, in series. An ammeter, a high-resistance voltmeter, a closed switch and battery are connected, as shown. The resistance of the battery and wires can be ignored.
The total power dissipated in the parallel part of the circuit is 50 W.
10.1.1 Define the term power. (2)
10.1.2 Calculate the effective resistance of the parallel combination. (2)
10.1.3 Calculate the potential difference across the resistors in parallel. (3)
10.1.4 Calculate the current through resistor R. (3)
The switch in the circuit is now OPENED.
10.1.5 How will the reading on the voltmeter (V) be influenced? Choose from INCREASE, DECREASE or REMAIN THE SAME. (1)
10.1.6 Explain the answer to QUESTION 10.1.5. (3)
10.2 A geyser, labelled 2 000 W, is used for an average of 5 hours per day. The cost of electricity is 80 cents per kWh.
10.2.1 Calculate the energy used by the geyser for 5 hours per day. (4)
10.2.2 Calculate the cost of electricity to operate the geyser for a month with 30 days. (2)
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