Answer:
R = 400 ohms.
Explanation: Voltage of the battery, V = 40 V. Current in the unknown resistor I = 100mA. Let R is the resistance of the resistor. It can be calculated using Ohm's law it gives the relationship between the voltage, resistance and current.. R = V/I. R = 40 V/10-¹A. R = 400 Ohm's. So, the value of the resistance of the resistor is 400 Ohm's