Ohm's Law Physics Example 2

Follow the full solution, then compare it with the other examples linked below.

Example 2

medium
A heater draws 5 A5 \text{ A} from a 240 V240 \text{ V} supply. What is its resistance, and how much power does it consume?

Solution

  1. 1
    Use Ohm's law for resistance: R=VI=2405=48 ΩR = \frac{V}{I} = \frac{240}{5} = 48 \text{ } \Omega.
  2. 2
    Use the electrical power formula: P=VIP = VI.
  3. 3
    P=240×5=1200 WP = 240 \times 5 = 1200 \text{ W}

Answer

R=48 Ω,P=1200 WR = 48 \text{ } \Omega, \quad P = 1200 \text{ W}
Ohm's law and power calculations go hand in hand. Knowing any two of VV, II, RR lets you find the third and calculate power.

About Ohm's Law

The fundamental relationship stating that the voltage (VV) across an ohmic conductor equals the current (II) flowing through it multiplied by its resistance (RR).

Learn more about Ohm's Law →

More Ohm's Law Examples

Example 1 easy

A [formula] battery is connected to a [formula] resistor. What current flows?

Example 3 medium

What voltage is needed to push [formula] through a [formula] resistor?

Example 4 medium

A resistor in a circuit has a current of [formula] flowing through it when connected to a [formula]

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