1800-150-456-789
FlagBACK
Flag Electric Current> Ab is a potentiometer wire of length 100 ...
question mark

Ab is a potentiometer wire of length 100 cm and resistance 10 ohm it is connected in series with a resistance r =40 ohms and a battery of emf 2v if a source of unknown emf e is balanced by 40cm of potentiometer the value of e

chandra manish , 5 Years ago
Grade 12th pass
anser 2 Answers
Arun

Last Activity: 5 Years ago

Dear student
 
2/100=e/40
1/50=e/40
40/50=e
0.8v=e
 
Hope it helps
 
Regards
Arun (askIITians forum expert)

Khimraj

Last Activity: 5 Years ago

given, resistance of potentiometer wire, R = 10 ohm 
length of potentiometer wire , l = 100cm
emf of cell, connected in series with potentiometer wire, E = 2V.
balancing length is obtained at 40cm.
so, I = E/(R + r) 
where I is the current through potentiometer .
I = 2/(10 + r) ....(1)
now resistance of 40cm wire = 40/100 × 10 = 4 ohms. 
given, emf of the cell is balanced by a length of wire, E' = 10mV = 10^-2 volts
using Ohm'slaw,
V = IR
10^-2 = I × 4 ohms 
or, I = 2.5 × 10^-3 A 
now putting the value of I in equation (1), 
2.5 × 10^-3 = 2/(10 + r) 
10 + r = 2/(2.5 × 10^-3) = 2000/2.5 = 800
or, r = 790 ohms 
hence, answer is 790ohms.
 

star
LIVE ONLINE CLASSES

Prepraring for the competition made easy just by live online class.

tv

Full Live Access

material

Study Material

removal

Live Doubts Solving

assignment

Daily Class Assignments


Other Related Questions on electric current

question mark
The fig. Shows a network of resistance in which the point A is earthed
 
electric current
0 Answer Available

Last Activity: 2 Years ago

question mark
When a p.d of 2v is applied across a resistor, 10j of energy are covered. What charge flows through the resistor?
 
electric current
0 Answer Available

Last Activity: 3 Years ago

question mark
Please provide it's solution. In video form 
Find the equivalent resistance of the given figure
electric current
0 Answer Available

Last Activity: 3 Years ago

question mark
The resistivity of material is 10 ohm m at 30 C when the temperature drops to 28 then the resistivity  drops by 2. The temperature coefficient of resistivity of material is 
electric current
0 Answer Available

Last Activity: 3 Years ago

question mark
Three cells of 2.0v each and internal resistance of 1.0 each are connected in series and in parallel calculate the new emf and new internal resistance in each connection
 
electric current
0 Answer Available

Last Activity: 3 Years ago