Question

An electrical circuit has.
• A power source
• A Resistor R and
• Three parallely connected resistors each of value 3R.
All these connected in series. If the current flowing through the docent is 5 Amperes. what will be its value. af R is doubled and each of Bris halved _______ . (asked in TCS NQT, Please Answers)​

Answer 1

The value of current is 4 amperes.

Given,

An electrical circuit has a power source, a resistor R, and three parallelly connected resistors each of value 3R.

The current flowing through the circuit is 5 amperes.

To Find,

The value of current if the value of resistance R is doubled and 3R is halved.

Solution,

The resultant resistance when three resistors each of 3R resistance is connected in parallel is

1/R' = 1/3R+1/3R+1/3R

1/R' = 3/3R

R' = R

Now, the equivalent resistance of the circuit will be

R eq = R+R = 2R

Now, using the ohm's law

V = RI

V = 2R*5 = 10R ----(i)

Now, the value of R becomes 2R and the value of three parallelly connected resistors is 3R/2 each.

1/R' = 2/3R+2/3R+2/3R

1/R' = 6/3R

R' = R/2

Now, the equivalent resistance is

Req = R/2+2R = 5R/2

Now,

V = RI

10R = 5R/2*I ( from (i) )

I = 4 amperes

Hence, the value of current is 4 amperes.

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