Two resistors with resistances 5Ω and 15Ω are to be connected to a battery of emf 9V so as to obtain: (i) minimum current

CBSE Class 10 CBSE Class 10 Science
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1

Two resistors with resistances 5Ω and 15Ω are to be connected to a battery of emf 9V so as to obtain:
(i) minimum current
(ii) maximum current.
(a) Show with the help of a diagram how you would connect the resistances in each case.
(b) Calculate the strength of the total current in the circuit in each of the two cases.

2

(a)

  1. For minimum current flow: In order to obtain the minimum current flowing through the circuit, the resistors must be connected in series with each other.
  2. For maximum current flow: In order to obtain the maximum current flowing through the circuit, the resistors must be connected in parallel with each other.

(b)

  1. For minimum current flow: Two resistors of resistances R1 and R2 are connected in series as:
    The equivalent resistance of the circuit is given as:
    R = R1 + R2 = 5 + 15 = 20Ω
    According to Ohm’s Law:
    V = IR
    Where,
    V = emf of the battery = 9V
    I = Total current flowing through the circuit
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  1. For maximum current flow: Two resistors of resistances R1 and R2 are connected in parallel as:

The equivalent resistance of the circuit is given as:

image

According to Ohm’s law
V = IR
V = emf of the battery =9v
I = Total current flowing through the circuit

image

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