Current Electricity
381 Questions
2006
JEE Mains
MCQ
AIEEE 2006
An electric bulb is rated $220$ volt - $100$ watt. The power consumed by it when operated on $110$ volt will be
A.
$75$ watt
B.
$40$ watt
C.
$25$ Watt
D.
$50$ Watt
2006
JEE Mains
MCQ
AIEEE 2006
The current ${\rm I}$ drawn from the $5$ volt source will be
A.
$0.33$ $A$
B.
$0.5$ $A$
C.
$0.67$ $A$
D.
$0.17$ $A$
2005
JEE Mains
MCQ
AIEEE 2005
Two sources of equal $emf$ are connected to an external resistance $R.$ The internal resistance of the two sources are ${R_1}$ and ${R_2}\left( {{R_1} > {R_1}} \right).$ If the potential difference across the source having internal resistance ${R_2}$ is zero, then
A.
$R = {R_2} - {R_1}$
B.
$R = {R_2} \times \left( {{R_1} + {R_2}} \right)/\left( {{R_2} - {R_1}} \right)$
C.
$R = {R_1}{R_2}/\left( {{R_2} - {R_1}} \right)$
D.
$R = {R_1}{R_2}/\left( {{R_1} - {R_2}} \right)$
2005
JEE Mains
MCQ
AIEEE 2005
An energy source will supply a constant current into the load if its internal resistance is
A.
very large as compared to the load resistance
B.
equal to the resistance of the load
C.
non-zero but less than the resistance of the load
D.
zero
2005
JEE Mains
MCQ
AIEEE 2005
A moving coil galvanometer has $150$ equal divisions. Its current sensitivity is $10$- divisions per milliampere and voltage sensitivity is $2$ divisions per millivolt. In order that each division reads $1$ volt, the resistance in $ohms$ needed to be connected in series with the coil will be -
A.
${10^5}$
B.
${10^3}$
C.
$9995$
D.
$99995$
2005
JEE Mains
MCQ
AIEEE 2005
In the circuit, the galvanometer $G$ shows zero deflection. If the batteries $A$ and $B$ have negligible internal resistance, the value of the resistor $R$ will be -
A.
$100\Omega $
B.
$200\Omega $
C.
$1000\Omega $
D.
$500\Omega $
2005
JEE Mains
MCQ
AIEEE 2005
Two voltmeters, one of copper and another of silver, are joined in parallel. When a total charge $q$ flows through the voltmeters, equal amount of metals are deposited. If the electrochemical equivalents of copper and silver are ${Z_1}$ and ${Z_2}$ respectively the charge which flows through the silver voltmeter is
A.
${q \over {1 + {{{Z_2}} \over {{Z_1}}}}}$
B.
${q \over {1 + {{{Z_1}} \over {{Z_2}}}}}$
C.
$q{{{Z_2}} \over {{Z_1}}}$
D.
$q{{{Z_1}} \over {{Z_2}}}$
2005
JEE Mains
MCQ
AIEEE 2005
A heater coil is cut into two equal parts and only one part is now used in the heater. The heat generated will now be
A.
four times
B.
doubled
C.
halved
D.
one fourth
2005
JEE Mains
MCQ
AIEEE 2005
In a potentiometer experiment the balancing with a cell is at length $240$ $cm.$ On shunting the cell with a resistance of $2\Omega ,$ the balancing length becomes $120$ $cm$. The internal resistance of the cell is
A.
$0.5\Omega $
B.
$1\Omega $
C.
$2\Omega $
D.
$4\Omega $
2005
JEE Mains
MCQ
AIEEE 2005
The resistance of hot tungsten filament is about $10$ times the cold resistance. What will be resistance of $100$ $W$ and $200$ $V$ lamp when not in use ?
A.
$20\Omega $
B.
$40\Omega $
C.
$200\Omega $
D.
$400\Omega $
2004
JEE Mains
MCQ
AIEEE 2004
The thermo $emf$ of a thermocouple varies with temperature $\theta $ of the hot junction as $E = a\theta + b{\theta ^2}$ in volts where the ratio $a/b$ is ${700^ \circ }C.$ If the cold junction is kept at ${0^ \circ }C,$ then the neutral temperature is
A.
${1400^ \circ }C$
B.
${350^ \circ }C$
C.
${700^ \circ }C$
D.
No neutral temperature is possible for this termocouple.
2004
JEE Mains
MCQ
AIEEE 2004
An electric current is passed through a circuit containing two wires of the same material, connected in parallel. If the lengths and radii are in the ratio of ${4 \over 3}$ and ${2 \over 3}$, then the ratio of the current passing through the wires will be
A.
$8/9$
B.
$1/3$
C.
$3$
D.
$2$
2004
JEE Mains
MCQ
AIEEE 2004
The Kirchhoff's first law $\left( {\sum i = 0} \right)$ and second law $\left( {\sum iR = \sum E} \right),$ where the symbols have their usual meanings, are respectively based on
A.
conservation of charge, conservation of momentum
B.
conservation of energy, conservation of charge
C.
conservation of momentum, conservation of charge
D.
conservation of charge, conservation of energy
2004
JEE Mains
MCQ
AIEEE 2004
Thermistors are usually made of
A.
metal oxides with high temperature coefficient of resistivity
B.
metals with high temperature coefficient of resistivity
C.
metals with low temperature coefficient of resistivity
D.
semiconducting materials having low temperature
2004
JEE Mains
MCQ
AIEEE 2004
In a meter bridge experiment null point is obtained at $20$ $cm$, from one end of the wire when resistance $X$ is balanced against another resistance $Y.$ If $X < Y$, then where will be the new position of the null point from the same end, if one decides to balance a resistance of $4$ $X$ against $Y$
A.
$40$ $cm$
B.
$80$ $cm$
C.
$50$ $cm$
D.
$70$ $cm$
2004
JEE Mains
MCQ
AIEEE 2004
The electrochemical equivalent of a metal is ${3.35109^{ - 7}}$ $kg$ per Coulomb. The mass of the metal liberated at the cathode when a $3A$ current is passed for $2$ seconds will be
A.
$6.6 \times {10^{57}}/kg$
B.
$9.9 \times {10^{ - 7}}\,kg$
C.
$19.8 \times {10^{ - 7}}\,kg$
D.
$1.1 \times {10^{ - 7}}\,kg$
2004
JEE Mains
MCQ
AIEEE 2004
The resistance of the series combination of two resistances is $S.$ When they are jointed in parallel the total resistance is $P.$ If $S = nP$ then the Minimum possible value of $n$ is
A.
$2$
B.
$3$
C.
$4$
D.
$1$
2004
JEE Mains
MCQ
AIEEE 2004
A material $'B'$ has twice the specific resistance of $'A'.$ A circular wire made of $'B'$ has twice the diameter of a wire made of $'A'$. Then for the two wires to have the same resistance, the ratio ${l \over B}/{l \over A}$ of their respective lengths must be
A.
$1$
B.
${l \over 2}$
C.
${l \over 4}$
D.
$2$
2004
JEE Mains
MCQ
AIEEE 2004
The total current supplied to the circuit by the battery is
A.
$4A$
B.
$2A$
C.
$1A$
D.
$6A$
2003
JEE Mains
MCQ
AIEEE 2003
A $3$ volt battery with negligible internal resistance is connected in a circuit as shown in the figure. The current ${\rm I}$, in the circuit will be
A.
$1$ $A$
B.
$1.5$ $A$
C.
$2$ $A$
D.
$1/3$ $A$
2003
JEE Mains
MCQ
AIEEE 2003
The nagative $Zn$ pole of a Daniell cell, sending a constant current through a circuit, decreases in mass by $0.13g$ in $30$ minutes. If the electrochemical equivalent of $Zn$ and $Cu$ are $32.5$ and $31.5$ respectively, the increase in the mass of the positive $Cu$ pole in this time is
A.
$0.180$ $g$
B.
$0.141$ $g$
C.
$0.126$ $g$
D.
$0.242$ $g$
2003
JEE Mains
MCQ
AIEEE 2003
A $220$ volt, $1000$ watt bulb is connected across a $110$ $volt$ mains supply. The power consumed will be
A.
$750$ watt
B.
$500$ watt
C.
$250$ watt
D.
$1000$ watt
2003
JEE Mains
MCQ
AIEEE 2003
The length of a wire of a potentiometer is $100$ $cm$, and the $e.$ $m.$ $f.$ of its standard cell is $E$ volt. It is employed to measure the $e.m.f.$ of a battery whose internal resistance in $0.5\Omega .$ If the balance point is obtained at $1=30$ $cm$ from the positive end, the $e.m.f.$ of the battery is
where $i$ is the current in the potentiometer wire.
A.
${{30E} \over {100.5}}$
B.
${{30E} \over {\left( {100 - 0.5} \right)}}$
C.
${{30\left( {E - 0.5i} \right)} \over {100}}$
D.
${{30E} \over {100}} - 0.5i$, where i is the current in the potentiometer
wire
2003
JEE Mains
MCQ
AIEEE 2003
The thermo $e.m.f.$ of a thermo -couple is $25$ $\mu V/{}^ \circ C$ at room temperature. A galvanometer of $40$ $ohm$ resistance, capable of detecting current as low as ${10^{ - 5}}\,A,$ is connected with the thermo couple. The smallest temperature difference that can be detected by this system is
A.
${16^0}C$
B.
${12^0}C$
C.
${8^0}C$
D.
${20^0}C$
2003
JEE Mains
MCQ
AIEEE 2003
An ammeter reads upto $1$ ampere. Its internal resistance is $0.81$ $ohm$. To increase the range to $10$ $A$ the value of the required shunt is
A.
$0.03\,\Omega $
B.
$0.3\,\Omega $
C.
$0.9\,\Omega $
D.
$0.09\,\Omega $
2003
JEE Mains
MCQ
AIEEE 2003
The length of a given cylindrical wire is increased by $100\% $. Due to the consequent decrease in diameter the change in the resistance of the wire will be
A.
$200\% $
B.
$100\% $
C.
$50\% $
D.
$300\% $
2002
JEE Mains
MCQ
AIEEE 2002
If ${\theta _1},$ is the inversion temperature, ${\theta _n}$ is the neutral temperature, ${\theta _c}$ is the temperature of the cold junction, then
A.
${\theta _i} + {\theta _c} = {\theta _n}$
B.
${\theta _i} - {\theta _c} = 2{\theta _n}$
C.
${{{\theta _i} + {\theta _C}} \over 2} = {\theta _n}$
D.
${\theta _c} - {\theta _i} = 2{\theta _n}$
2002
JEE Mains
MCQ
AIEEE 2002
The mass of product liberated on anode in an electrochemical cell depends on (where $t$ is the time period for which the current is passed).
A.
${\left( {It} \right)^{1/2}}$
B.
$It$
C.
$I/t$
D.
${I^2}t$
2002
JEE Mains
MCQ
AIEEE 2002
If an ammeter is to be used in place of a voltmeter, then we must connect with the ammeter a
A.
low resistance in parallel
B.
high resistance in parallel
C.
high resistance in series
D.
low resistance in series
2002
JEE Mains
MCQ
AIEEE 2002
A wire when connected to $220$ $V$ mains supply has power dissipation ${P_1}.$ Now the wire is cut into two equal pieces which are connected in parallel to the same supply. Power dissipation in this case is ${P_2}.$ Then ${P_2}:{P_1}$ is
A.
$1$
B.
$4$
C.
$2$
D.
$3$
2002
JEE Mains
MCQ
AIEEE 2002
If in the circuit, power dissipation is $150W,$ then $R$ is
A.
$2\,\Omega $
B.
$6\,\Omega $
C.
$5\,\Omega $
D.
$4\,\Omega $