The circuit above illustrates a standard resistor R, voltage source E and a lamp L connected in series. If the temperature of R is increased, the brightness...

Answer Details

When the temperature of the resistor R is increased, its resistance increases. Since the resistor R and the lamp L are connected in series, the total resistance of the circuit also increases. This causes a decrease in the current passing through the circuit since current is inversely proportional to resistance (Ohm's law). As a result, the brightness of the lamp L decreases slightly. Therefore, the correct answer is "decrease slightly."