, what is
the maximum current that can be drawn from the battery?
is
connected to a resistor. If the current in the circuit is 0.5 A, what is the
resistance of the resistor? What is the terminal voltage of the battery when
the circuit is closed?
, 2
and 3 are
combined in series. What is the total resistance of the combination?
(b)
If the combination is connected to a battery of e.m.f. 12 V and negligible
internal resistance, obtain the potential drop across each resistor.
, 4
and 5 are
combined in parallel. What is the total resistance of the combination?
(b)
If the combination is connected to a battery of e.m.f. 20 V and negligible
internal resistance, determine the current through each resistor, and the total
current drawn from the battery.
.
What is the temperature of the element if the resistance is found to be 117 ,
given that the temperatures coefficient of the material of the resistor is 1.70
× 10?4 °C?1.
at 27.5°C,
and a resistance of 2.7 at 100°C.
Determine the temperature co-efficient of resistivity of silver.
.
. Determine
the resistance of X. Why are the connections between resistors in a Wheatstone
or meter bridge made of thick copper strips?
(b)
Determine the balance point of the bridge above if X and Y are interchanged.
(c)
What happens if the galvanometer and cell are interchanged at the balance point
of the bridge? Would the galvanometer show any current?
is being
charged by a 120 V dc supply using a series resistor of 15.5 .
What is the terminal voltage of the battery during charging? What is the
purpose of having a series resistor in the charging circuit?
are joined in series to prop supply to a resistance of 8.5.
What are the current drawn from the s u and its terminal voltage?
(b)
A secondary cell after long use has an e.m.f. of 1.9 V and a large internal resistance
of 380 . What maximum
current can be drawn from the cell? Could the cell drive the starting motor of
a car?
Relative
density of Al = 2.7, of Cu = 8.9.)
| Current | Voltage | Current | Voltage |
| A | V | A | V |
| 0.2 | 3.94 | 3.0 | 59.2 |
| 0.4 | 78.7 | 4.0 | 78.8 |
| 0.6 | 11.8 | 5.0 | 98.6 |
| 0.8 | 15.7 | 6.0 | 118.5 |
| 1.0 | 19.7 | 7.0 | 138.2 |
| 2.0 | 39.4 | 8.0 | 158.0 |
, 2,
3, how will
be combine them to get an equivalent resistance of (i) (11/3) ,
(ii) (11/5), (iii) 6,
(iv) (6/ 11 ) ?
(c)
Determine the equivalent resistance of networks shown in figure.
by the infinite network shown in figure. Each resistor has 1 resistance.
maintaining
a potential drop across the resistor wire AB. A standard cell which maintains a
constant e.m.f. of 1.02 V (for very moderate currents upto a few mA) gives a
balance point at 67.3 cm length of the wire. To ensure very low currents drawn
from the standard cell, a very high resistance of 600 k
is put in series with it, which is shorted close to the balance point. The
standard cell is then replaced by a cell of unknown e.m.f. 
and
the balance point found simllarly, turns out to be at 82.3 cm length of the wire.
(a)
What is the value ?
(h)
What purpose does the high resistance of 600 k have?
(c)
Is the balance point affected by this high resistance?
(d)
Is the balance point affected by the internal resistance of the driver cell?
(e)
Would the method work in the above situation if the driver cell of the
potentiometer had an e.m.f. of 1.0 V instead of 2.0 V?
(f)
Would the circuit work cell for determining an extremely small e.m.f., say of
the order of a few mV (such as the typical e.m.f. of a thermo-couple?) If not,
how will you modify the circuit?
is found
to be 58.3 cm, while that with the unknown resistance X is 68.5 cm. Determine
the value of X. What might you do if you failed to find a balance point with
the given cell of emf 
?
of
a 1.5 V cell. The balance point of the cell in open circuit is 76.3 cm. When a
resistor of 9.5 
is used in
the external circuit of the cell, the balance point shifts to 64.8 cm length of
the potentiometer wire. Determine the internal resistance of the cell.
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