a cars radio draws 0.25 A of current in the autos 12 volt electrical system. How much power in watts does the radio use?

P = E*I = 12*0.25 = 3.0 Watts.

To calculate the power in watts that the car radio uses, you need to use the formula:

Power (in watts) = Current (in amperes) x Voltage (in volts)

Given that the car's radio draws a current of 0.25 A in the 12-volt electrical system, you can substitute these values into the formula:

Power = 0.25 A x 12 V

Multiply 0.25 by 12 to get the power in watts:

Power = 3 W

Therefore, the car radio uses 3 watts of power.