Current Electricity

The balancing length for a cell is 560 cm in a potentiometer experiment. When an external
resistance of 10 \(\Omega\) is connected in parallel to the cell, the balancing length changes by 60 cm. If
the internal resistance of the ceil is $$...

In a building there are 15 bulbs of 45 W, 15 bulbs of 100 W, 15 small fans of 10 W and 2 heaters
of 1 kW. The voltage of electric main is 220 V. The minimum fuse capacity (rated value) of the
building will be :

In the figure shown, the current in the 10 V battery is close to :

A circuit to verify Ohm's law uses ammeter and voltmeter in series or parallel connected correctly
to the resistor. In the circuit :

An electrical power line, having a total
resistance of 2 \(\Omega\), delivers 1 kW at 220 V. The
efficiency of the transmission line is
approximately :

A galvanometer of resistance G is converted
into a voltmeter of range 0 – 1 V by connecting
a resistance R1 in series with it. The additional
resistance that should be connected in series
with R1 to increase the range of the voltmeter
to 0 ...

In the circuit, given in the figure currents in
different branches and value of one resistor are
shown. Then potential at point B with respect to
the point A is :

A galvanometer is used in laboratory for
detecting the null point in electrical
experiments. If, on passing a current of 6 mA it
produces a deflection of 2o, its figure of merit
is close to :

A battery of 3.0 V is connected to a resistor dissipating 0.5 W of power. If the terminal voltage of the battery is 2.5 V, the power dissipated within the internal resistance is :

The value of current i1
flowing from A to C in the circuit diagram is :

Four resistances 40 \(\Omega\), 60 \(\Omega\), 90 \(\Omega\) and 110 \(\Omega\) make the arms of a quadrilateral ABCD. Across AC is
a battery of emf 40 V and internal resistance negligible.The potential difference across BD in V is
____...

Model a torch battery of length \(l\) to be made up
of a thin cylindrical bar of radius ‘a’ and a
concentric thin cylindrical shell of radius ‘b’
filled in between with an electrolyte of
resistivity \(\rho\) (see figure). If the battery is...

Two resistors 400\(\Omega\) and 800\(\Omega\) are connected in series across a 6 V battery. The potential difference measured by a voltmeter of 10 k\(\Omega\) across 400 \(\Omega\) resistor is close to :

Consider four conducting materials copper,
tungsten, mercury and aluminium with
resistivity \(\rho\)C, \(\rho\)T, \(\rho\)M and \(\rho\)A respectively. Then :

A potentiometer wire PQ of 1 m length is
connected to a standard cell E1. Another cell E2
of emf 1.02 V is connected with a resistance ‘r’
and switch S (as shown in figure). With switch
S open, the null position is obtained at a
distance of...

A resistance is shown in the figure. Its value and tolerance are given respectively by :

When the switch S, in the circuit shown, is closed, then the value of current i will be :

Drift speed of electrons, when 1.5 A of current flows in a copper wire of cross section 5 mm2, is \(\upsilon\). If the electron density in copper is 9 \(\times\) 1028/m3 the value of \(\upsilon\). in mm/s is close to (Take charge of ele...

In the given circuit the the internal resistance of the 18 V cell is negligible. If R1 = 400 \(\Omega\), R3 = 100 \(\Omega\) and R4 = 500 \(\Omega\) and the reading of an ideal voltmeter across R4 is 5V, then the value of R2 will be :

A carbon resistance has a following colour code. What is the value of the resistance ?

A wire of resistance R is bent to form a square
ABCD as shown in the figure. The effective
resistance between E and C is :
(E is mid-point of arm CD)

A moving coil galvanometer has resistance 50\(\Omega\)
and it indicates full deflection at 4mA current.
A voltmeter is made using this galvanometer
and a 5 k\(\Omega\) resistance. The maximum voltage,
that can be measured using this voltm...

A metal wire of resistance 3 \(\Omega\) is elongated to
make a uniform wire of double its previous
length. This new wire is now bent and the ends
joined to make a circle. If two points on this
circle make an angle 60° at the centre, the
e...

The resistance of a galvanometer is 50 ohm and
the maximum current which can be passed
through it is 0.002 A. What resistance must be
connected to it in order to convert it into an
ammeter of range 0 – 0.5 A ?

In a conductor, if the number of conduction
electrons per unit volume is 8.5 × 1028 m–3 and
mean free time is 25ƒs (femto second), it's
approximate resistivity is :-
(me = 9.1 × 10–31 kg)

For the circuit shown, with R1 = 1.0W, R2 = 2.0 W,
E1 = 2 V and E2 = E3 = 4 V, the potential
difference between the points 'a' and 'b' is
approximately (in V):

A 200 \(\Omega\) resistor has a certain color code. If one
replaces the red color by green in the code, the
new resistance will be :

In the circuit shown, a four-wire potentiometer
is made of a 400 cm long wire, which extends
between A and B. The resistance per unit length
of the potentiometer wire is r = 0.01 \(\Omega\)/cm. If
an ideal voltmeter is connected as shown w...

A cell of internal resistance r drives current
through an external resistance R. The power
delivered by the cell to the external resistance
will be maximum when :-

In the figure shown, what is the current
(in Ampere) drawn from the battery ? You are
given:
R1 = 15\(\Omega\), R2 = 10 \(\Omega\), R3 = 20 \(\Omega\), R4 = 5\(\Omega\),
R5 = 25\(\Omega\), R6 = 30 \(\Omega\), E = 15 V

An ideal battery of 4 V and resistance R are connected in series in the primary circuit of a potentiometer of length 1 m and esistance 5 \(\Omega\). The value of R, to give a potential difference of 5 mV across 10 cm of potentiometer wire...

The galvanometer deflection, when key K1 is closed but K2 is open, equals \(\theta\)0 (see figure). On closing K2 also and adjusting R2 to 5\(\Omega\), the deflection in galvanometer becomes \({{{\theta _0}} \over 5}.\) . The resistance o...

Two electric bulbs, rated at (25 W, 220 V) and (100 W, 220 V), are connected in series across a 220 V voltage source. If the 25 W and 100 W bulbs draw powers P1 and P2 respectively, then :

In a meter bridge, the wire of length 1 m has a non-uniform cross-section such that, the variation \({{dR} \over {d\ell }}\) of its resistance R with length \(\ell\) is \({{dR} \over {d\ell }}\) \(\propto\) \({1 \over {\sqrt \ell }}\)....

In the given circuit diagram, the currents, I1 = – 0.3 A, I4 = 0.8 A and I5 = 0.4 A, are flowing as shown. The currents I2, I3 and I6, respectively, are :

A galvanometer, whose resistance is 50 ohm, has 25 divisions in it. When a current of 4 \(\times\) 10–4 A passes through it, its needle ( pointer) deflects by one division. To use this galvanometer as a voltmeter of range 2.5 V, it should...

The resistive network shown below is connected to a D.C. source of 16 V. The power consumed by the
network is 4 Watt. The value of R is:

A galvanometer of resistance 100 \(\Omega\) has 50 divisions on its scale and has sensitivitv of 20 \(\mu\)A/division. It is
to be converted to a voltmeter with three ranges of 0-2V, 0-10 V and 0-20 V. The appropriate circuit to do so
is

To verify Ohm's law, a student connects the voltmeter across the battery as, shown in the figure. The
measured voltage is plotted as a function of the current, and the following graph is obtained :

If V0 is almost zero, identify the correc...

A moving coil galvanometer, having a resistance G, produces full scale deflection when a current Ig flows
through it. This galvanometer can be converted into (i) an ammeter of range 0 to I0(I0 > Ig) by connecting a
shunt resistance RA to it...

The resistance of the meter bridge AB in given figure is 4 \(\Omega\). With a cell of emf \(\varepsilon\) = 0.5 V and rheostat
resistance Rh = 2 \(\Omega\) the null point is obtained at some point J. When the cell is replaced by another ...

In a Wheatstone bridge(see fig.), Resistances P and Q are approximately equal. When R = 400 \(\Omega\), the bridge
is balanced. On interchanging P and Q, the value of R, for balance, is 405 \(\Omega\). The value of X is close to :

Two equal resistances when connected in series to a battery, consume electric power of 60 W. If these resistances are now connected in parallel combination to the same battery, the electric power consumed will be :

A galvanometer having a resistance of 20 \(\Omega\) and 30 divisions on both sides has figure of merit 0.005 ampere/division. The resistance that should be connected in series such that it can be used as a voltmeter upto 15 volt, is:

In the circuit shown, the potential difference between A and B is :

In the experimental set up of metre bridge shown in the figure, the null point is obtained at a distance of 40 cm from A. If a 10 \(\Omega\) resistor is connected in series with R1, the null point shifts by 10 cm. The resistance that shoul...

In the given circuit the cells have zero internal resistance. The currents (in Amperes) passing through resistance R1 and R2 respectively, are -

A potentiometer wire AB having length L and resistance 12 r is joined to a cell D of emf \(\varepsilon\) and internal resistance r. A cell C having emf \(\varepsilon\)/2 and internal resistance 3r is connected. The length AJ at which the ...

A uniform metallic wire has a resistance of 18 \(\Omega\) and is bent into an equilateral triangle. Then, the resistance between any two vertices of the triangle is -

A 2 W carbon resistor is color coded with green, black, red and brown respectively. The maximum current which can be passed through this resistor is -