What is the voltage across a 10-ohm resistor if a current of 1 ampere flows through it?
Why Ohm's Law says voltage equals current times resistance, E = I x R. Here 1 ampere flowing through 10 ohms gives E = 1 x 10 = 10 volts. Whenever you know current and resistance, multiply them to get the voltage drop across the component.
Watch out The choices showing 11 volts and 9 volts come from adding or subtracting the two numbers instead of multiplying them, which is not what Ohm's Law says.
E = I x R: volts = amps times ohms. One amp through ten ohms is ten volts.