Physics · Grades 9–12
Electrical energy and power · Revision sheet
Combine voltage, current, resistance and time without mixing units.
Learn the idea
Power
Electrical power in a steady DC element is potential difference times current.
Ohmic substitutions
For a resistor, substitute V = IR to obtain P = I²R or V²/R under the same assumptions.
Energy
Energy equals power times time when power is constant. Use compatible units such as W and s, or kW and h.
No hidden claims
A nameplate value is not necessarily the actual power under every operating condition; supplied values define each model.
Explain without looking
- A 10 V potential difference transfers 50 J. Find charge transferred.
- At fixed resistance, doubling voltage changes power by what factor, and why?
Further reading and review references
These are reference links, not copied exercises, institutional endorsement or proof of independent review.
Independent educational review required. Grade bands are approximate; these are not officially aligned curricula.