Two resistance 100 ohm and 200 …

Question:- Two resistances of 100 ohms and 200 ohm are connected in series to a 150 V supply.A voltmeter of resistance of 200 ohm is connected across 100 ohm resistor.what will be the reading of voltmeter

Soln:-

Given

• Two resistances of 100 ohm and 200 ohm are connected in series.

• A voltmeter having internal resistance of 200 ohm is connected across 100 ohm resistor.

Concept

• Voltmeter measures potential difference across the two point it is connected.Hence, here, it will the measure the potential difference across 100 ohm resistor.
• In series combination of resistance , equivalent resistance is measured by the relation

• In parallel combination , we measure equivalent resistance as

Solutions

• Voltmeter (200 ohm) and 100 ohm resistor are parallel.

=> 

=> 

=> 

• Net resistance will be the sum of  and 200 ohm

= 

= 

= 

=> I = 

=> I =  A

=> I =  A

• Reading of the Voltmeter = Current flowing × Net resistance across it

= 

= 

= 37.5 V