JEE Current Electricity PYQs with Solutions PDF, Download Now

An electric power line having total resistance of $$2\Omega$$, delivers 1 kW of power at 250 V. The percentage efficiency of transmission line is ____ .

A wire of uniform resistance AΩ/m is bent into a circle of radius r and another piece of wire with length 2r is connected between points A and B (AOB) as shown in figure. The equivalent resistance between points A and B is ____Ω .

A regular hexagon is fonned by six wires each of resistance $$r \Omega$$ and the corners are joined to the centre by wires of same resistance. If the current enters at one corner and and leaves at. the opposite corner,the equivalent. resistance of the hexagon between the two opposite corners will be

The equivalent resistance between the points A and B in the following circuit is $$\frac{x}{5}$$Ω. The value ofx is________.

Which of the following resistivity $$(\rho) v/s$$ temperature (T) curves is most suitable to be used in wire bound standard resistors?

A wire of resistance $$9\,\Omega$$ is bent to form an equilateral triangle. Then the equivalent resistance across any two vertices will be  $$\underline{\hspace{2cm}}\,\Omega.$$

A wire of resistance R is bent into an equilateral triangle and an identical wire is bent into a square. The ratio of resistance between the two end points of an edge of the triangle to that of the square is Options.

Find the equivalent resistance between two ends of the following circuit

The resistances of the platinum wire of a platinum resistance thermometer at the ice point and steam point are 8Ω and 10Ω respectively. After inserting in a hot bath of temperature 400°C, the resistance of platinum wire is:

To measure the internal resistance of a battery, potentiometer is used. For R = 10Ω, the balance point is observed at l = 500 cm and for R = 1Ω the balance point is observed at l = 400 cm. The internal resistance of the battery is approximately:

In an ammeter, 5% of the main current passes through the galvanometer. If resistance of the galvanometer is G, the resistance of ammeter will be:

To measure the temperature coefficient of resistivity $$\alpha$$ of a semiconductor, an electrical arrangement shown in the figure is prepared. The arm BC is made up of the semiconductor. The experiment is being conducted at 25°C and resistance of the semiconductor arm is $$3 \text{ m}\Omega$$. Arm BC is cooled at a constant rate of $$2 \text{ °C s}^{-1}$$. If the galvanometer G shows no deflection after 10 s, then $$\alpha$$ is

A wire of resistance $$R$$ and length $$L$$ is cut into $$5$$ equal parts. If these parts are joined parallely, then resultant resistance will be :

A wire of length $$10$$ cm and radius $$\sqrt{7} \times 10^{-4}$$ m connected across the right gap of a meter bridge. When a resistance of $$4.5 \; \Omega$$ is connected on the left gap by using a resistance box, the balance length is found to be at $$60$$ cm from the left end. If the resistivity of the wire is $$R \times 10^{-7} \; \Omega$$ m, then value of $$R$$ is :

Wheatstone bridge principle is used to measure the specific resistance $$S_1$$ of given wire, having length $$L$$, radius $$r$$. If X is the resistance of wire, then specific resistance is : $$S_1 = X\frac{\pi r^2}{L}$$. If the length of the wire gets doubled then the value of specific resistance will be :

Three voltmeters, all having different internal resistances are joined as shown in figure. When some potential difference is applied across A and B, their readings are $$V_1$$, $$V_2$$ and $$V_3$$. Choose the correct option.

The electric current through a wire varies with time as $$I = I_0 + \beta t$$, where $$I_0 = 20$$ A and $$\beta = 3$$ A s$$^{-1}$$. The amount of electric charge crossed through a section of the wire in $$20$$ s is:

A galvanometer having coil resistance $$10 \Omega$$ shows a full scale deflection for a current of $$3$$ mA. For it to measure a current of $$8$$ A, the value of the shunt should be:

The deflection in moving coil galvanometer falls from $$25$$ divisions to $$5$$ division when a shunt of $$24 \Omega$$ is applied. The resistance of galvanometer coil will be:

In the given circuit, the breakdown voltage of the Zener diode is $$3.0$$ V. What is the value of $$I_z$$?

An electric toaster has resistance of $$60 \text{ } \Omega$$ at room temperature $$(27°C)$$. The toaster is connected to a $$220 \text{ V}$$ supply. If the current flowing through it reaches $$2.75 \text{ A}$$, the temperature attained by toaster is around: (if $$\alpha = 2 \times 10^{-4} \text{ °C}^{-1}$$)

When a potential difference $$V$$ is applied across a wire of resistance $$R$$, it dissipates energy at a rate $$W$$. If the wire is cut into two halves and these halves are connected mutually parallel across the same supply, the energy dissipation rate will become:

Two conductors have the same resistances at $$0°C$$ but their temperature coefficients of resistance are $$\alpha_1$$ and $$\alpha_2$$. The respective temperature coefficients for their series and parallel combinations are :

By what percentage will the illumination of the lamp decrease if the current drops by 20%?

An electric bulb rated $$50$$ W $$- 200$$ V is connected across a $$100$$ V supply. The power dissipation of the bulb is:

Two wires $$A$$ and $$B$$ are made up of the same material and have the same mass. Wire $$A$$ has radius of $$2.0$$ mm and wire $$B$$ has radius of $$4.0$$ mm. The resistance of wire $$B$$ is $$2\Omega$$. The resistance of wire $$A$$ is _____ $$\Omega$$.

A wire of resistance $$20\Omega$$ is divided into 10 equal parts, resulting pairs. A combination of two parts are connected in parallel and so on. Now resulting pairs of parallel combination are connected in series. The equivalent resistance of final combination is ______ $$\Omega$$.

If the radius of earth is reduced to three-fourth of its present value without change in its mass then value of duration of the day of earth will be _________ hours 30 minutes.

A wire of resistance $$R$$ and radius $$r$$ is stretched till its radius became $$r/2$$. If new resistance of the stretched wire is $$xR$$, then value of $$x$$ is _______

The number of electrons flowing per second in the filament of a $$110 \text{ W}$$ bulb operating at $$220 \text{ V}$$ is : (Given $$e = 1.6 \times 10^{-19} \text{ C}$$)

In the given figure an ammeter A consists of a $$240 \Omega$$ coil connected in parallel to a $$10 \Omega$$ shunt. The reading of the ammeter is ___________ mA.

Resistance of a wire at $$0°C$$, $$100°C$$ and $$t°C$$ is found to be $$10\Omega$$, $$10.2\Omega$$ and $$10.95\Omega$$ respectively. The temperature $$t$$ in Kelvin scale is ________.

Water boils in an electric kettle in 20 minutes after being switched on. Using the same main supply, the length of the heating element should be _____ to _____ times of its initial length if the water is to be boiled in 15 minutes.

A potential divider circuit is connected with a dc source of 20 V, a light emitting diode of glow in voltage 1.8 V and a zener diode of breakdown voltage of 3.2 V. The length (PR) of the resistive wire is 20 cm. The minimum length of PQ to just glow the LED is _____ cm

A galvanometer has a coil of resistance $$200\Omega$$ with a full scale deflection at $$20\mu A$$. The value of resistance to be added to use it as an ammeter of range $$(0 - 20)$$ mA is :

The equivalent resistance between A and B is :

The effective resistance between $$A$$ and $$B$$, if resistance of each resistor is $$R$$, will be

A nucleus at rest disintegrates into two smaller nuclei with their masses in the ratio of $$2 : 1$$. After disintegration they will move :

At room temperature $$(27°C)$$, the resistance of a heating element is $$50\Omega$$. The temperature coefficient of the material is $$2.4 \times 10^{-4} \text{ °C}^{-1}$$. The temperature of the element, when its resistance is $$62\Omega$$, is ______ °C.

To determine the resistance $$(R)$$ of a wire, a circuit is designed below. The $$V - I$$ characteristic curve for this circuit is plotted for the voltmeter and the ammeter readings as shown in figure. The value of $$R$$ is ______ $$\Omega$$.