Question

Find out the voltage in a circuit where
current will be 2Aand resistance are 4ohm, 5ohm, and 8ohm

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Answer 1

Given:-

• Resistance of 1st Resistor ,R1 = 4Ω

• Resistance of 2nd Resistor ,R2 = 5Ω

• Resistance of 3rd Resistor ,R3 = 8Ω

• Current ,I = 2 A

To Find:-

• Voltage ,V

Solution:-

Case 1st

Here we have to calculate the Voltage through given resistors . There are two condition to find the voltage . When Resistors are connected in Series .

Req = R1 + R2 + R3

Substitute the value we get

➨ Req = 4+5+8

➨ Req = 17Ω

The Equivalent resistance of Resistors when connected in series is 17 ohms

Using Ohm's Law

• V = IR

Substitute the value we get

➨ V = 2 × 17

➨ V = 34 v

Therefore the voltage in a circuit when they are connected in series is 34 volts.

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Case 2nd

when Resistors are connected in Parallel

• Req = 1/R1 + 1/R2 + 1/R3 +..

Substitute the value we get

➨ 1/Req = 1/4 + 1/5 + 1/8

➨ 1/Req =10+8 +5 /40

➨ 1/Req = 23/40

➨ Req = 40/23

➨ Req = 1.73 Ω

Equivalent Resistance when Resistors are connected in parallel is 1.73 ohms

Using Ohm's Law

• V = IR

Substitute the value we get

➨ V = 2×1.73

➨ V = 3.46 v

Therefore , the voltage across the Resistors when connected in Parallel is 3.46 volts.

Answer 2

Question

Find out the voltage in a circuit where current will be 2A and resistance are 4ohm, 5ohm, and 8ohm.

Solution

Resistance (1) = 4ohm

Resistance (2) = 5ohm

Resistance (3) = 8ohm

Current = 2A

SI unit of current is ampere(A).

Voltage (V) = IR

'I' denotes current

'R' denotes resistance

If the circuit is in series then we have to add up the resistance.

If the circuit is parallel then we have to use the formula

$\frac{1}{r(equi)} = \frac{1}{r1} + \frac{1}{r2} + \frac{1}{r3}$

When the sum is in series.

Resistance = (4+5+8)ohm = 17ohm

Current = 2A

Voltage(V) = IR

= (17×2)

= 34

When the sum is in parallel.

Current = 2A

$\frac{1}{r(equi)} = \frac{1}{4} + \frac{1}{5} + \frac{1}{8} = \frac{10 + 8 + 5}{40} \\ \frac{1}{r(equi)} = \frac{23}{40} \\ r \: = \frac{40}{23}$

$voltage(v) = ir \\ = (2 \times \frac{40}{23}) \\ = 3.478261$