Some students carry out investigations with an electric motor - Edexcel - GCSE Physics - Question 1 - 2012 - Paper 1

The input power can be calculated using the formula:

$ext{Power} = ext{Voltage} imes ext{Current}$

Substituting the values:

$ext{Power} = 6 ext{ V} imes 0.5 ext{ A} = 3 ext{ W}$

Thus, the input power to the motor is 3 W.

The energy wasted can be calculated as follows:

$ext{Wasted energy} = ext{Input energy} - ext{Energy transferred to the weight}$

Substituting the values:

$ext{Wasted energy} = 200 ext{ J} - 50 ext{ J} = 150 ext{ J}$

Therefore, 150 J of energy is wasted.

Efficiency can be calculated using the formula:

ext{Efficiency} = rac{ ext{Useful output energy}}{ ext{Total input energy}} imes 100

Substituting the values:

ext{Efficiency} = rac{50 ext{ J}}{200 ext{ J}} imes 100 = 25\%

Thus, the efficiency of the motor is 25%.