Yes. The most common form of electric bicycle in Europe is a "pedelec". This is where you must pedal the bicycle at least to some degree under the law. Turning the pedals on the bicycle will activate the motor.
The degree to which you pedal or the motor does the work can be adjusted by a small device on the handlebars. On the flat, you may wish to conserve your battery and have the motor do very little. On hills, you may wish to increase the power and have the motor do nearly all the work.