Practice Questions

Q26.The current density in a cylindrical wire of radius r = 4. 0 mm is 1. 0 × 106 A2 m2 . The current through the outer portion of the wire between radial distances r and r is xπ A ; where x is 2

Q26.A potentiometer wire of length 300 cm is connected in series with a resistance 780 Ω and a standard cell of emf 4 V. A constant current flows through potentiometer wire. The length of the null point for cell of emf 20mV is found to be 60 cm. The resistance of the potentiometer wire is _____ Ω.

Q26.A set of 20 tuning forks is arranged in a series of increasing frequencies. If each fork gives 4 beats with respect to the preceding fork and the frequency of the last fork is twice the frequency of the first, then the frequency of last fork is _____ Hz.

Q26.The volume charge density of a sphere of radius 6 m is 2 μC cm-3. The number of lines of force per unit surface area coming out from the surface of the sphere is _____ × 1010 N C-1 . [Given : Permittivity of vacuum 𝜖0 = 8 . 85 × 10-12C2 N-1 - m-2]

Q26.Two electric dipoles of dipole moments 1 . 2 × 10-30 cm and 2 . 4 × 10-30 cm are placed in two difference uniform electric fields of strengths 5 × 104 N C-1 and 15 × 104 N C-1 respectively. The ratio of maximum 1 torque experienced by the electric dipoles will be 𝑥. The value of 𝑥 is _____ .

Q26.A circular coil of 1000 turns each with area 1 m2 is rotated about its vertical diameter at the rate of one revolution per second in a uniform horizontal magnetic field of 0. 07 T. The maximum voltage generation will be _____ V.

Q26.A long cylindrical volume contains a uniformly distributed charge of density ρ C m−3 . The electric field inside the cylindrical volume at a distance x = 2ε0ρ m from its axis is _____ V m−1 . JEE Main 2022 (27 Jul Shift 1) JEE Main Previous Year Paper

Q26.In a potentiometer arrangement, a cell of emf 1. 20 V gives a balance point at 36 cm length of wire. This cell is now replaced by another cell of emf 1. 80 V . The difference in balancing length of potentiometer wire in above conditions will be _____ cm.

Q26.When a gas filled in a closed vessel is heated by raising the temperature by 1°C, its pressure increases by 0 . 4% The initial temperature of the gas is _____ 𝐾. Q27.27 identical drops are charged at 22 V each. They combine to form a bigger drop. The potential of the bigger drop will be _____ V.

Q26.Resistance are connected in a meter bridge circuit as shown in the figure. The balancing length l1 is 40 cm. Now an unknown resistance x is connected in series with P and new balancing length is found to be 80 cm measured from the same end. Then the value of x will be _____ Ω.

Q26.A meter bridge setup is shown in the figure. It is used to determine an unknown resistance R using a given resistor of 15 Ω. The galvanometer (G) shows null defection when tapping key is at 43 cm mark from end A . If the end correction for end A is 2 cm, then the determined value of R will be Ω.

Q26.The current I flowing through the given circuit will be _____ A . JEE Main 2022 (29 Jul Shift 1) JEE Main Previous Year Paper

Q27.Magnetic flux (in weber) in a closed circuit of resistance 20 Ω varies with time t(s) as ϕ = 8t2 −9t + 5. The magnitude of the induced current at t = 0. 25 s will be _____ mA .

Q27.A parallel plate capacitor with width 4 cm, length 8 cm and separation between the plates of 4 mm is connected to a battery of 20 V . A dielectric slab of dielectric constant 5 having length 1 cm, width 4 cm and thickness 4 mm is inserted between the plates of parallel plate capacitor. The electrostatic energy of this system will be _____ ϵ0 J. (Where ϵ0 is the permittivity of free space)

Q27.In a double slit experiment with monochromatic light, fringes are obtained on a screen placed at some distance from the plane of slits. If the screen is moved by 5 × 10−2 m towards the slits, the change in fringe width is 3 × 10−3 cm . If the distance between the slits is 1 mm , then the wavelength of the light will be____ nm .

Q27.A 110 V, 50 Hz, AC source is connected in the circuit (as shown in figure). The current through the resistance 55 Ω, at resonance in the circuit, will be _____ A.

Q27.The intensity of the light from a bulb incident on a surface is 0. 22 W m−2 . The amplitude of the magnetic field in this light-wave is _____ ×10−9 T (Given : Permittivity of vacuum ϵ0 = 8. 85 × 10−12 C2 N−1 m−2 , speed of light in vacuum c = 3 × 108 m s−1 )

Q27.An electrical bulb rated 220 V, 100 W , is connected in series with another bulb rated 220 V , 60 W . If the voltage across combination is 220 V , the power consumed by the 100 W bulb will be about _____ W.

Q27.As shown in the figure, a potentiometer wire of resistance 20 Ω and length 300 cm is connected with resistance box (R.B.) and a standard cell of emf 4 V. For a resistance '𝑅' of resistance box introduced into the circuit, the null point for a cell of 20 mV is found to be 60 cm. The value of '𝑅' is _____ Ω. 1

Q27.The current density in a cylindrical wire of radius 4 mm is 4 × 106 A m−2 . The current through the outer portion of the wire between radial distances R and R is _____ π A. 2

Q27.Two identical thin biconvex lenses of focal length 15 cm and refractive index 1. 5 are in contact with each other. The space between the lenses is filled with a liquid of refractive index 1. 25 . The focal length of the JEE Main 2022 (24 Jun Shift 1) JEE Main Previous Year Paper combination is _____ cm.

Q27.In the given circuit, the magnitude of VL and VC are twice that of VR . Given that f = 50 Hz , the inductance of the coil is 1 mH . The value of K is _____ . Kπ JEE Main 2022 (28 Jun Shift 2) JEE Main Previous Year Paper

Q27.A capacitor of capacitance 500 𝜇F is charged completely using a de supply of 100 V. It is now connected to an inductor of inductance 50 mH to form an LC circuit. The maximum current in LC circuit will be _____ A.

Q27.The equivalent capacitance between points 𝐴 and 𝐵 in below shown figure will be _____ 𝜇F.

Q27.In meter bridge experiment for measuring unknown resistance ' S ', the null point is obtained at a distance 30 cm from the left side as shown at point D. If R is 5. 6 kΩ, then the value of unknown resistance ' S ' will be _____ Ω.