Subjective Assignment
BOARD LEVEL QUESTIONS ON POTENTIOMETER
Q.1
Name the instrument that can measure the e.m.f. of a cell.
Q.2
Why the battery used in the main circuit of the potentiometer should have high emf than that of the cells whose emf is required ?
Q.3
Which instrument will you use to measure e.m.f . of a cell and why ?
Q.4
How the potentiometer can be used to
(a) find the ratio of emf of two cells
(b) find the internal resistance of a cell.
Q.5
A potentiometer wire has a length of 200cm and it is connected to a source of 2volts.Find the potential gradient across the wire and also the length required to balance a source of emf 0.85 volts.
Q.6
A potentiometer balance an emf of 1.2volts with a length of 130cm. Find the potential gradient across the wire and the emf of the source connected in the circuit if the length of the wire is 300cm.
Q.7
A source of emf 2volts is used in the main circuit of a potentiometer used to find the internal resistance of a cell of 1.5volts.The balance point of the cell in an open circuit is 76.3cm.When a resistance of 9.5W is used in the external circuit of the cell, the balance point is shifted to 64.8cm. Determine the internal resistance of the cell.
Q.8
A potentiometer has a wire of length 200cm and resistance of 10W.It is connected to an external resistance of 990W in series and a battery of 1.2volt is applied in the circuit. Find the potential gradient across the wire and the length of the wire required to balance an emf of 0.2mVolt.
Q.9
A potentiometer wire has a length of 100cm and a resistance of 10W.It is connected to an external resistance in series and a cell of emf 2V.A source of emf 10mV is balanced by a length of 40 cm of this wire. Find the value of external resistance.
Q.10
A potentiometer wire has a uniform cross-section of 10-2m2 a length of 100cm and resistivity of 0.001Wm. It is connected with an external resistance in series and a battery.If a potential gradient of 25mV/cm is existing in the wire then find the external resistance if emf of the battery used in the main circuit is 1.2V.
Q.11
The figure illustrates a potentiometeric circuit by means of which we can vary a voltage V applied to a certain device possessing a resistance R. The potentiometer has a length l and a resistance Ro and a voltage Vo is applied to its terminals.Find the voltage V fed to the device as a function of distance x.Analyse separately the case R>>Ro.
