Physics practice questions with solutions

Physics practice questions with solutions:

Find the resultant resistance for the following given arrangement. Find the current, when this arrangement is connected with 9V battery.

                                                (TS March-2017)

Sol:-

• First let's find out where first and second ends of each resistance connected.

• If we observe the above diagram carefully, we can understand that all the first ends of each  resistors connected at a particular point and second ends also connected at other point.

• When two or more resistors connected between the same points, then this connection is called Parallel connection of resistors.  In this type of circuit current will divide among the resistors and Voltage will remain the same.

• The above statement concludes that the three resistors are connected parallel in the circuit.

Now we can re-draw the circuit as shown below.

• The resultant resistance in the parallel connection of the resistors is  R= 1/R1 + 1/R2 + 1/R3 

• R=1/3 + 1/3 +1/3           

• R=1+1+1/3

• R=3/3 ⇒ 1Ω

• The resultant resistance in the circuit is R= 1Ω

• If potential difference in the circuit is V= 9 Volts

• What is the current(I) flowing in the circuit?

• According to Ohm's law V=IR or  I=V/R

• Here V=9V and R=1Ω 

• I= 9/1

• I=9 A   

•  The current flowing in the circuit is 9 Amperes