Ohm's Law Quiz
Questions: 16 · 10 minutes
1. Which statement correctly expresses Ohm’s law for a conductor under constant physical conditions?
Voltage equals current divided by resistance.
Voltage equals current multiplied by resistance.
Current equals voltage multiplied by resistance.
Resistance equals current multiplied by voltage.
2. Why might a filament lamp fail to produce a straight-line voltage-current graph?
Its current always remains zero until the rated voltage is reached
Its voltage and current are measured in incompatible units
Its resistance changes as the filament heats up
Its resistance is exactly zero when switched off
3. A 9 V potential difference is applied across a 3 Ω resistor. What current flows?
3 A
6 A
27 A
0.33 A
4. A graph plots voltage on the vertical axis and current on the horizontal axis for an ohmic resistor. What does the slope represent?
Resistance
Electrical charge
Electrical power
Conductance
5. A device draws 0.8 A when connected to 24 V. What is its resistance at that operating point?
30 Ω
19.2 Ω
24.8 Ω
0.033 Ω
6. A 6 Ω resistor is connected across a 12 V supply. After finding the current with Ohm’s law, calculate the resistor’s power using P = VI.
2 W
6 W
72 W
24 W
7. A 3 Ω resistor and a 7 Ω resistor are connected in series across a 20 V supply. What current flows in the circuit?
0.5 A
4 A
2 A
10 A
8. Two resistors are connected in series to a battery. Which electrical quantity is the same through both resistors?
Voltage across each resistor
Power used by each resistor
Resistance of each resistor
Current through each resistor
9. A current of 0.5 A flows through a 12 Ω resistor. What voltage is across the resistor?
0.042 V
6 V
5.5 V
24 V
10. Which unit is used to measure electrical resistance?
Ohm
Ampere
Volt
Watt
11. Which operation correctly calculates resistance from known voltage and current?
Divide current by voltage.
Divide voltage by current.
Multiply voltage by current.
Subtract current from voltage.
12. A wire accidentally creates a very low-resistance path across a voltage source. What does Ohm’s law predict about the current in that path?
It will become very small because the path is short
It will equal the resistance measured in ohms
It will remain fixed regardless of resistance
It can become very large because resistance is very low
13. A student wants to measure the voltage across a resistor. How should the voltmeter be connected?
In series before the resistor
In series after the resistor
Across the power source only, with the resistor disconnected
In parallel across the resistor
14. Two resistors are connected in parallel directly across a 12 V supply. What voltage is across each branch?
The voltage is divided according to resistance
Each branch has 12 V
Each branch has 6 V
The branch voltage depends only on total current
15. A 4 Ω resistor carries a current of 2 A. What is the potential difference across it?
6 V
2 V
8 V
0.5 V
16. The voltage across a resistor remains constant while its resistance doubles. According to Ohm’s law, what happens to the current?
It doubles
It remains unchanged
It is halved
It becomes four times as large