The voltage in a circuit is given by the expression , V = IR , Where I is the current inbthe circuit and R is the resistance of circuit.
In this case I = V/R
In this circuit voltage V = 10 volt
Resistance of the circuit = 20 ohm
So current , I = 10/20 = 0.5 amperes
So if a 10-volt battery is placed across a 20-ohm resistance, the current will be 0.5 amperes
