There is a potential difference of 3.6 V across the lamp in Figure 11.
The current through the lamp is 0.80 A.
Calculate the resistance of the lamp.
How to approach this question
1. Start with the equation V = I × R.
2. Rearrange the equation to make resistance (R) the subject.
3. Identify the values given: Potential difference (V) = 3.6 V and Current (I) = 0.80 A.
4. Substitute these values into your rearranged equation.
5. Calculate the resistance. The unit is Ohms (Ω).
Full Answer
Equation: resistance = potential difference / current
Substitution: R = 3.6 V / 0.80 A
Answer: R = 4.5 Ω
We use Ohm's Law, which links potential difference (V), current (I), and resistance (R):
V = I × R
To find the resistance, we need to rearrange the equation by dividing both sides by current (I):
R = V / I
Now, substitute the given values:
- V = 3.6 V
- I = 0.80 A
R = 3.6 / 0.80
R = 4.5 Ω
Common mistakes
✗ Incorrectly rearranging the equation (e.g., multiplying V and I).
✗ Dividing current by voltage instead of voltage by current.
✗ Calculation errors.
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