Oscilloscope An oscilloscope is used to display the shape of electrical signals - showing how they vary with time. It can be used to measure voltage and time periods.
Loudspeaker A transducer which converts electrical energy to sound.
Aerial (Antenna) A device to receive or transmit radio signals. It is also known as an antenna.
A NOT gate can only have one input. The o on the output means not. The output of a NOT gate is the inverse (opposite) of its input, so the output is true when the input is false. A NOT gate is also called an inverter.