Current electricity practice · Mixed difficulty

A current of $\mathrm{1}\mathrm{.5}\,\,\mathrm{A}$ flows through a copper voltameter. The thickness of copper deposited on the electrode surface of size $50\,\,\mathrm{cm}\,\, \times \,10\,\,\mathrm{cm}$ is $\mathrm{20}\,\,\mathrm{min}$ will be (density of copper $= 9000\,\,\mathrm{kg} - {\mathrm{m}^{ - 3}}\,\,\mathrm{and}\,\mathrm{ ECE }\,\mathrm{of}\,\mathrm{ copper} = 0.00033\,\,\mathrm{g}\,\,{\mathrm{C}^{ - 1}})$

Potentiometer measures the potential difference more accurately than a voltmeter because

An uncharged capacitor having capacitance $C$ is connected across a battery of emf $V$. Now the battery is disconnected and reconnected across same battery but with reverse polarity, then the ratio of total thermal energy produced to the total energy supplied by the battery is

Potential gradient is defined as

A piece of copper and the other of germanium are cooled from the room temperature to $80 \mathrm{~K}$, then which of the following would be wrong statements?
(a) Resistance of each increases
(b) Resistance of each decreases
(c) Resistance of copper increases while that of germanium decreases
(d) Resistance of copper decreases while that of germanium increases

The number of electrons flowing per second in the filament of a $110 \mathrm{~W}$ bulb operating at $220 \mathrm{~V}$ is :

(Given $\mathrm{e}=1.6 \times 10^{-19} \mathrm{C}$)

A battery having e.m.f. $5\,\,V$ and internal resistance 0.5 Ω is connected with a resistance of $4.5\,\,\mathrm{\Omega }$ then the voltage at the terminals of battery is

The thermistors are usually made of

Heat produced (cals) in a resistance $R$ when a current $I$ amperes flows through it for $t$ seconds is given by the expression

Statement-1: Current flows in a conductor only when there is an electric field within the conductor.
Statement-2: The drift velocity of electrons in the presence of electric field decreases.

In the experiment of the meter bridge if length corresponding to null deflection is $x$, what would be its value if the radius of meter bridge wire is doubled?

Specific resistance of copper, constantan and silver are $1.78\,\, \times \,\,{10^{ - 8}},\,\,39.1\,\, \times \,\,{10^{ - 8}}\,\,\mathrm{and}\,\,{10^{ - 8}}\,\,\mathrm{\Omega - m }$ respectively. Which of these is the best conductor of heat and electricity?

The current in a circuit containing a battery connected to $2 \Omega$ resistance is 0.9 A. When a resistance of $7 \Omega$ is connected to the same battery, the current observed in the circuit is 0.3 A. Then the internal resistance of the battery is:

The area of cross-section, length and density of a piece of a metal of atomic weight $60\, \mathrm{gm}$ are $10^{-6} \mathrm{~m}^2, 1.0$ $\mathrm{m}$ and $5 \times 10^3 \mathrm{~kg} / \mathrm{m}^3$ respectively and every atom contributes one free electron. (Given Avogadro number $=6 \times 10^{23} / \mathrm{mol}$ ). Find the drift velocity of electrons in the metal when the current of $16 \mathrm{~A}$ passes through it.

Statement-1: Two unequal resistances are connected in series across a cell, then potential drop across the larger resistance is more.
Statement-2: The current will be same in both unequal resistances.

Peltier coefficient for the junction of a pair of metals is proportional to

The value of internal resistance of an ideal cell is

A motor having an armature of resistance $2\,\,\mathrm{\Omega }$ is designed to operate at $220\,\,V$ mains. At full speed, it develops a back e.m.f. of $210\,\,V$. When the motor is running at full speed, the current in the armature is

If 12 resistors of $12\, \Omega$ each are connected in each edge of a cubical circuit then effective resistance across any of its edge is :-

The electrolyte used in Lechlanche cell is

Constantan wire is used in making standard resistances because its

A potentiometer consist of a wire of length 2m and resistance . It is connected to an ideal cell of e.m.f 4V. The potential difference per unit length of the wire will be

Two resistors of resistance ${R_1}$ and ${R_2}$ having ${R_1} > {R_2}$ are connected in parallel. For equivalent resistance $R$, the correct statement is

When an electrical appliance is switched on, it responds almost immediately, because

Two identical cells connected in series send 10 A current through a $5\Omega$ resistor. When they are connected in parallel, they send 8A current through same resistance. What is internal resistance of each cell ?

Statement-1: When a wire is stretched with in the proportionality limit such that its length becomes $n$ times that of its initial value, the resistance of wire may become $n^2$ times of its initial resistance.
Statement-2: The poisson's ratio of the wire's material can be $1 / 2$.

Which of the following are true, when the cells are connected in series?

It is possible that any some constant value of emf, but the potential difference between the plates is zero?

An electron beam has an aperture $1.0 \mathrm{~mm}^2$. A total of $6 \times 10^{16}$ electrons go through any perpendicular cross section per second. Find the current density in the beam. (in $\mathrm{A} / \mathrm{m}^2$ )

A direct current of $4 \mathrm{~A}$ and an alternating current of peak value 4 A flow through resistance of $3 \Omega$ and $2 \Omega$ respectively. The ratio of heat produced in the two resistances in same interval of time will be :