Falling Behind in Studies? Join Our Performance Improvement Batch. Enroll For Free
One of our academic counsellors will contact you within 1 working day.
Click to Chat
1800-1023-196
+91-120-4616500
CART 0
Use Coupon: CART20 and get 20% off on all online Study Material
Welcome User
OR
LOGIN
Complete Your Registration (Step 2 of 2 )
A cell of emf E is connected across a resistance R. The potential difference across the terminals of the cell isfound to be V volt. Internal resistance of cell is a] (E-V)R b] (E-V)R/V c] 2(E-V)R/E d] 2(E-V)V/R
Assume a circuit (with the given conditions) :Emf(E) , Internal Resistance(r), External Resistance(R)When no current is drawn from the cell :Emf(E) = Internal Potential Difference(V”) //across the plates of the emf.But, when current(i) is drawn :Emf(E) = V” + V //due to potential drop, external potential difference is obtained (V) ; as mentioned.Now, since : V” = i . r ; Then, E = V” + V will become,> E = (i . r) + V> E – V = i . r> (E – V) / i = rsince, i = V / R ;> (E – V) / (V / R) = r> {(E – V) . R} / V = r //ans(b)
The electromotive force (e) or e.m.f. is the energy provided by a cell or battery per coulomb of charge passing through it, it is measured in volts (V). It is equal to the potential difference across the terminals of the cell when no current is flowing.E = I(R+r)E = electromotive force in volts, VI = current in amperes, AR = resistance of the load in the circuit in ohms,r = internal resistance of the cell in ohms.That is, E = IR+Ir, E = V + Ir.Rearranging the equation we get, r=RE−V.Substituting I=V/R in the above equation, we get, r=RVE−V=V(E−V)R.Hence, internal resistance r=V(E−V)R.
Post Question
Dear , Preparing for entrance exams? Register yourself for the free demo class from askiitians.
points won -