Units (Electricity)
4 marks · NormalThe table shows data collected by a student measuring current through two different components, X and Y, as the voltage increases. Both are measured at room temperature.
| Voltage (V) | Current in X (A) | Current in Y (A) |
|---|---|---|
| 0 | 0.00 | 0.00 |
| 0.5 | 0.08 | 0.15 |
| 1.0 | 0.16 | 0.30 |
| 1.5 | 0.24 | 0.37 |
| 2.0 | 0.32 | 0.39 |
Using the table, calculate the resistance of component X at 1.5 V.
State the unit for resistance and suggest, giving a reason, which component is likely to be a filament bulb.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) 6.25 Ω
(b) The unit of resistance is the ohm (Ω). Component Y is likely the filament bulb, because the current increases less with voltage at higher voltages, indicating increasing resistance (non-ohmic).
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · Uses R = V / I with correct table values (V=1.5, I=0.24). (follow-through)
A1 (a) · 1 mark · Accurate answer, quoted to two decimal places (6.25 Ω).
B1 (b) · 1 mark · States correct unit used for resistance (ohm, Ω).
E1 (b) · 1 mark · Identifies Y as filament bulb with valid explanation about current/voltage relationship.
Worked solution
a) R = V / I = 1.5 V / 0.24 A = 6.25 Ω
b) The unit is ohm (Ω). Component Y is probably the filament bulb because the increase in current with voltage slows down at higher voltage, which is characteristic of bulbs as their resistance rises with temperature.