Electricity: Ohm's Law
Numerical Problems
These numerical problems are based on the chapter Electricity class 10 science of NCERT book and CBSE syllabus.
Example 1: Calculate the resistance if 5 A of electric current flows through a conductor having potential difference between two points is equal to 15 V.
Solution: Given, electric current (I) = 5 A
Potential difference (V) = 15 V
Resistance (R) =?
We know from Ohm's Law that
`R=V/I`
Or, `R=(15V)/(5A)=3Ω`
Example 2: If the potential difference between the terminals of an electric motor is 220 V and an electric current of 5 A is flowing through it what will be the resistance of electric motor?
Solution: Given, electric current (I) = 5 A
Potential difference (V) = 220 V
Resistance (R) =?
We know from Ohm's Law that
`R=V/I`
Or, `R=(220V)/(5A)=44Ω`
Example 3: An electric current of 15 A is flowing through an electric fan. If the potential difference between two terminals of electric fan is 240 V, what will be resistance?
Solution: Given, electric current (I) = 15 A
Potential difference (V) = 240 V
Resistance (R) =?
We know from Ohm's Law that
`R=V/I`
Or, `R=(240V)/(15A)=16Ω`
Example 4: If the resistance of an electric iron is 48 Ω and an electric current of 5 A is flowing through it, what will be the potential difference between two terminals of electric iron.
Solution: Given, electric current (I) = 5 A
Resistance (R) = 48Ω
Potential difference (V) =?
We know from Ohm's Law that
`R=V/I`
Or, `V=RxxI`
Or, `V=48Ωxx5A=240V`
Example 5: Calculate the potential difference between two points of a terminal, if an electric current of 10 A is flowing through it having resistance of 20Ω.
Solution: Given, electric current (I) = 10 A
Resistance (R) = 20Ω
Potential difference (V) =?
We know from Ohm's Law that
`R=V/I`
Or, `V=RxxI`
Or, `V=20Ωxx10A=200V`
Example 6: If the resistance between two terminals of an electric heater is 15Ω and an electric current of 15 A is flowing through it then what will be the voltage of electric current?
Given, electric current (I) = 15 A
Resistance (R) = 15Ω
Voltage, i.e. Potential difference (V) =?
We know from Ohm's Law that
`R=V/I`
Or, `V=RxxI`
Or, `V=15Ωxx15A=225V`
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