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Three resistances of 15 ohms, 10 ohms and 30 ohms are connected in a parallel combination, then What is its equivalent resistance ?

Three resistances of 15 ohms, 10 ohms and 30 ohms are connected in a parallel combination, then What is its equivalent resistance ? Correct Answer <p>5 ohm</p>

The Correct answer is 5 ohm.

Key Points

  • For resistances that are connected in parallel, the formula is, Reciprocal of the equivalent resistance = Sum of reciprocal of all the resistances.
  • Now, we have,
    • R1= 15 ohm;     R2= 10 ohm    and      R3= 30 ohm
  • Then equivalent resistance is 1/R = 1/R1 + 1/R2 + 1/R3
  • 1/R = 1/15 + 1/10 + 1/30
  • 1/R = 6/30
  • 1/R = 1/5
  • R= 5 ohm

 

Important Points  

Series Resistance Parallel Resistance
The same amount of current flows through all the components The current flowing through each component combines to form the current flow through the source.
In an electrical circuit, components are arranged in a line In an electrical circuit, components are arranged parallel to each other
When resistors are put in a series circuit, the voltage across each resistor is different even though the current flow is the same through all of them. When resistors are put in a parallel circuit, the voltage across each of the resistors is the same. And even the polarities are the same
If one component breaks down, the whole circuit will burn out. Other components will function even if one component breaks down, each has its own independent circuit

Series Resistance diagram:

[ alt="F1 Krupalu Anil 04.01.21 D1" src="//storage.googleapis.com/tb-img/production/21/01/F1_Krupalu_Anil_04.01.21_D1.png" style="width: 207px; height: 111px;">

Parallel Resistance diagram:

  [ alt="F1 Krupalu Anil 04.01.21 D2" src="//storage.googleapis.com/tb-img/production/21/01/F1_Krupalu_Anil_04.01.21_D2.png" style="width: 229px; height: 160px;">

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