Current Electricity · Physics · COMEDK

Three bulbs of $$40 \mathrm{~W}, 60 \mathrm{~W}$$, and $$100 \mathrm{~W}$$ are arranged in series with a $$220 \mathrm{~V}$$ source. The maximum light is obtained from

The resistance of a $$10 \mathrm{~m}$$ long wire is $$10 \Omega$$. Its length is increased by $$25 \%$$ by stretching the wire uniformly. The new resistance is

Four resistors, each of resistance R, are connected as shown in the figure below.

A voltmeter of resistance $$1000 \Omega .0 .5 \mathrm{~V} /$$ div is to be converted into a voltmeter to make it to read $$=1 \mathrm{~V} / \mathrm{div}$$. The value of high resistance to be connected in series with it is

The resistance of the galvanometer and shunt of an ammeter are $$90 \mathrm{~ohm}$$ and $$10 \mathrm{~ohm}$$ respectively, then the fraction of the main current passing through the galvanometer and the shut respectively are:

A $$500 \mathrm{~W}$$ heating unit is designed to operate on a $$400 \mathrm{~V}$$ line. If line voltage drops to $$160 \mathrm{~V}$$, the percentage drop in heat output will be:

A cell of emf E and internal resistance r is connected to two external resistances $$\mathrm{R_1}$$ and $$\mathrm{R_2}$$ and a perfect ammeter. The current in the circuit is measured in four different situations:

(a) without any external resistance in the circuit.

(b) with resistance $$\mathrm{R_1}$$ only

(c) with $$\mathrm{R_1}$$ and $$\mathrm{R_2}$$ in series combination.

(d) with $$\mathrm{R_1}$$ and $$\mathrm{R_2}$$ in parallel combination.

The currents measured in the four cases in ascending order are

The current through a conductor is '$$\mathrm{a}$$' when the temperature is $$0^{\circ} \mathrm{C}$$. It is '$$\mathrm{b}$$' when the temperature is $$100^{\circ} \mathrm{C}$$. The current through the conductor at $$220^{\circ} \mathrm{C}$$ is

On increasing the temperature of a conductor, its resistance increases because

A galvanometer having a resistance of $$8 \Omega$$ is shunted by a wire of resistance $$2 \Omega$$. If the total current is $$1 \mathrm{~A}$$, the part of it passing through the shunt will be

Two cells with the same emf $$E$$ and different internal resistances $$r_1$$ and $$r_2$$ are connected in series to an external resistance $$R$$. If the potential difference across the first cell is zero then value of $$R$$.

The current sensitivity of a galvanometer having 20 divisions is $$10 \mu \mathrm{A} /$$ div. If the resistance of the galvanometer is $$100 \Omega$$ then the value of the resistance to be used to convert this galvanometer in to an voltmeter to read up to $$1 \mathrm{~V}$$ is :

The electric flux from cube of side $$1 \mathrm{~m}$$ is '$$\Phi$$' When the side of the cube is made $$3 \mathrm{~m}$$ and the charge enclosed by the cube is made one third of the original value, then the flux from the bigger cube will be :

A resistor of wire $$24 \mathrm{~cm}$$ length and resistance $$8 \Omega$$ is stretched in to a uniform wire of $$48 \mathrm{~cm}$$ length, then the new resistance will be :

The SI unit of electrical conductivity is :

The current passing through the 100$$\Omega$$ resistor in the given electrical circuit is :

A battery is made of 12 cells having emf $$5 \mathrm{~V}$$ each. If three cells are unknowingly connected wrong, the resultant emf of the battery will be:

The current drawn by the primary coil of an ideal transformer, which steps up $$22 \mathrm{~V}$$ into $$220 \mathrm{~V}$$, to operate a device having a load resistance $$110 \Omega$$ is:

A galvanometer having a resistance of 4 $$\Omega$$ is shunted by a wire of resistance 2 $$\Omega$$. If the total current is 1.5 A, the current passing through shunt is

A cell of emf 2 V is connected with a load of resistance 1.5 $$\Omega$$. The power delivered by the cell to the load is maximum, then power transferred to the load is

The resistance of a wire is R ohm. If it is melted and stretched to n times its original length, its new resistance will be

For the given electrical arrangement, what is the value of current I?

If voltage $$V=(200\pm 8)V$$ and current $$I=(20\pm0.5)A$$, then the percentage error in resistance R is

Point out the right statements about the validity of Kirchhoff’s junction rule,

If $$P=Q=R=10\Omega$$ and $$S=20\Omega$$, then what resistance should be joined with S to balance the Wheatstone's network?

To the potentiometer wire of length L and 10$$\Omega$$ resistance, a battery of emf 2.5 V and a resistance R are connected in series. If a potential difference of 1 V is balanced across L/2 length, the value of R in $$\Omega$$ will be