A battery is connected to a small, noisy heater (it makes sound). During a certain period of time after the heater has reached its operating temperature, the battery transfers 10 joules of energy to the heater due to an electric circuit interaction and transfers 0.4 joules of energy to the surroundings due to heat interactions. During that same time period, the heater transfers 8 joules of energy to the surroundings due to heat interactions and transfers 2 joules of energy to the sound receivers due to a sound interaction. What is the efficiency of the heater