Question
1. A student investigated how the current in a resistor varies with the potential difference across the resistor. The diagram shows part of the circuit used. (a) The student connected an ammeter and a voltmeter into the circuit. What is the correct way to connect the ammeter and the voltmeter into the circuit? Tick (checkmark) one box. Ammeter & Voltmeter }(l) In parallel with the resistor & In series with the resistor In parallel with the cell & In series with the resistor In series with the resistor & In parallel with the resistor In series with the resistor & In parallel with the cell (b) The student increased the resistance of the variable resistor. How did increasing the resistance affect the current in the circuit? qquad qquad (c) How should the student change the circuit to give negative values for current and potential difference?
Answer
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(199 Votes)
Logan
Expert · Tutor for 3 years
Answer
(a) Ammeter is connected in series with the resistor & Voltmeter is connected in parallel with the resistor(b) As the resistance increased, the current in the circuit decreased. (d) The relationship between current and potential difference for a resistor, at constant temperature, is 'Linear'.
Explanation
## Step1: The wiring of an ammeter and voltmeter in a circuit is a crucial part of this question. An ammeter is always connected in series with the circuit that we are measuring, as it shows the total current flowing through the circuit. In contrast, a voltmeter is connected in parallel to the component where we need to know the potential difference (voltage).## Step2: Based on the rules of Ohm's Law, as the resistance of a circuit element (in this case, a variable resistor) increases, provided the voltage is kept constant, the current through the element decreases. The voltage being constant is a reasonable assumption in many cases, including this one where the power supply (cell in this case) typical maintains a constant voltage.## Step 3:The relation between potential difference (voltage) and current in a resistor, at constant temperature, is direct or linear. This means voltage is directly proportional to the current and indication of this is given by Ohm's law which is : V=IR where V is voltage, I is current and R is resistance. The graph of V and I for such relationship is a straight line. Hence, the relationship is called 'linear' relationship.