6. A simple electrical circuit consists of a variable resistor R connected to a cell of emf 6.0 V and internal resistance 1.5 Ω.nnnn(a) Define *electromotive force (emf)*. [1]nn(b) The variable resistor is set to 4.5 Ω. Calculate:n (i) the current in the circuit. [2]n (ii) the power dissipated in the internal resistance. [2]
Part a
1 minutes
1 marks
Question
(a) Define *electromotive force (emf)*. [1]
Hint Hint
Hint
Think about the energy conversion that happens inside a battery or cell.
Answer Answer
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Complete Answer
Emf is the work done per unit charge in moving charge completely around the circuit / energy converted from chemical (or other forms) to electrical per unit charge by the source.
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Part b(i)
2 minutes
2 marks
Question
(b) The variable resistor is set to 4.5 Ω. Calculate:n (i) the current in the circuit. [2]
Hint Hint
Hint
Use Ohm’s law for the entire circuit. Remember to include both the external and internal resistance.
Answer Answer
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Complete Answer
1.0 A
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Part b(ii)
2 minutes
2 marks
Question
(ii) the power dissipated in the internal resistance. [2]
Hint Hint
Hint
Use the formula for power dissipated in a resistor (P = I²R) and the current calculated in part (b)(i). Apply it to the internal resistance.
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