Current electricity practice · Mixed difficulty

A $25\,\,W,\,\,220\,\,V$ bulb and a $100\,\,W,\,\,220\,\,V$ bulb are connected in parallel across a $440\,\,V$ line

$\mathrm{160}\,\,\mathrm{W - }\,\mathrm{60}\,\,\mathrm{V}$ lamp is connected at $\mathrm{60}{\mkern 1mu} \mathrm{V}\,\,\,\mathrm{DC}$ supply. The number of electrons passing through the lamp in $\mathrm{1}\,\,\mathrm{min}$ is (the charge of electron $e = 1.6\,\, \times \,\,{10^{ - 19}}\,\,\mathrm{C}$

Statement-1: A piece of copper and other of germanium are cooled from room temperature to $100 \,\mathrm{K}$ conductivity of copper increases and that of germanium decreases.
Statement-2: Copper has positive temperature coefficient where as germanium has negative temperature coefficient.

An inductance of 0.1 henry is connected with D.C. source of 120 volt. If the current flowing in the inductive coil is $0.5\, \mathrm{amp}$, then resistance of the coil is:

In copper, each copper atom releases one electron. If a current of 1.1 A is flowing in the copper wire of uniform cross-sectional area of diameter 1 mm, then drift velocity of electrons will approximately be:

(Density of copper $=$ $9 \times 10^3 \mathrm{~kg} / \mathrm{m}^3,$ Atomic weight of copper = 63)

There are two electric bulbs rated $60 \mathrm{~W}, 120 \mathrm{~V}$ and $90 \mathrm{~W}$, $120 \mathrm{~V}$. They are connected in parallel with $240 \mathrm{~V}$ supply, then

A 2 volt battery, a $15\mathrm{ }\Omega$ resistor and a potentiometer of 100 cm length, all are connected in series. If the resistance of potentiometer wire is $5\mathrm{ }\Omega$, then the potential gradient of the potentiometer wire is

It is easier to start a car engine on a hot day than on a cold day. This is because the internal resistance of the car battery

A student has $\mathrm{10}\,\,\mathrm{resistors}$ of resistance $'r'$. The minimum resistance made by him from given resistors is

The electric intensity $E$, current density $j$ and specific resistance $k$ are related to each other by the relation

When a metal conductor connected to the left gap of a meter bridge is heated, the balancing point

A capacitor is connected to a cell of emf $E$ having some internal resistane $r$. The potential difference across the

For a metallic wire, the ratio $\frac{V}{i}(V =$ applied potential difference and $i$ =current flowing ) is

The accurate measurement of emf can be obtained using

An ammeter reads $\mathrm{0}\mathrm{.90}\,\,\mathrm{A}$ when connected in series with a silver voltmeter that deposits $\mathrm{2}\mathrm{.60 }\,\mathrm{g}$ of silver in $\mathrm{40}\,\,\mathrm{min}$. By what percentage is the ammeter reading is correct? Atomic weight of silver $\mathrm{ = 108}\,\,\,\mathrm{and}\,\,\mathrm{1}\,\,\mathrm{F}\,\mathrm{ = }\,\mathrm{96500}\,\,\mathrm{C}$ ?

Assertion: EMF of battery decreases with time.
Reason: Internal resistance increases with time.

A metal wire is subjected to a constant potential difference. When the temperature of the metal wire increases, the drift velocity of the electron in it

Find the true statements

A resistor ${R_1}$ dissipates power $P$ when connected to a certain generator. If the resistor ${R_2}$ is put in series with ${R_1}$, the power dissipated by ${R_1}$

Statement-1: If the length of a conductor is doubled, the drift velocity will become half of the original value (keeping potential difference unchanged).
Statement-2: At constant potential difference drift velocity is inversely proportional to the length of the conductor.

A constant voltage is applied between two ends of a metallic wire. If the wire is replaced by another wire of same material, half the length and doubled the radius, the rate of heat developed in the wire will be:

A lead acid accumulatory (storage battery) is connected to a battery charge for over night charging. Which of the following observations will indicate that the battery was partly charged during the next morning

To get the maximum current from a parallel combination of $n$ identical cells each of internal resistance $r$ and external resistance $R$, when

In water voltmeter, the electrolysis of …… takes place

A transformer operating at primary voltage of $4 \mathrm{~kV}$ and secondary voltage of $90 \mathrm{~V}$ serves a load of $90 \mathrm{~KW}$ at secondary. Assuming the transformer to be operating at $90 \%$ efficiency with purely resistive load, the loads in the primary and secondary are

Which of the following has a negative temperature coefficient

Assertion (A)In a meter bridge experiment, null point for an unknown resistance is put inside an enclosure maintained at a higher temperature. The null point can be obtained at the same ${p}$ as before by decreasing the value of the standard resistance.

Reason (R) Resistance of metal increases with increase in temperature.

A student in a town in India, where the price per
unit (1 unit = 1 kW-h) of electricity is `5.00,
purchases a 1 kVA UPS (uninterrupted power
supply) battery. A day before the exam, 10
friends arrive to the student’s home with their
laptops and all connect their laptops to the UPS.
Assume that each laptop has a constant power
requirement of 90 W. Consider the following
statements

I. All the 10 laptops can be powered by the
UPS if connected directly.

II. All the 10 laptops can be powered if
connected using an extension box with a
3A fuse.

III. If all the 10 friends use the laptop for 5 hours,
then the cost of the consumed electricity is
about `22.50.

Select the correct option with the true
statements.

By mistake a voltmeter is connected in series and an ammeter is connected in parallel with a resistance in an electrical circuit. What will happen to the instrument?

A conductor wire having ${10^{29}}$ free $\mathrm{electrons}/{\mathrm{m}^3}$ carries a current of $\mathrm{20}\,\,\mathrm{A}\,$. If the cross-section of the wire is $1\,\,\mathrm{m}{\mathrm{m}^2}$, then the drift velocity of electrons will be