Practice Questions

Q25.A wire of length 30 cm, stretched between rigid supports, has it's nth and (n + 1)th harmonics at 400 Hz and 450 Hz, respectively. If tension in the string is 2700 N , it's linear mass density is _____ kg m−1 .

Q25.A parallel plate capacitor is made up of stair like structure with a plate area A of each stair and that is x ε0 A , The connected with a wire of length b, as shown in the figure. The capacitance of the arrangement is b 15 value of x is _____ .

Q25.The frequency of echo will be _____ Hz if the train blowing a whistle of frequency 320 Hz is moving with a velocity of 36 km h-1 towards a hill from which an echo is heard by the train driver. Velocity of sound in air JEE Main 2022 (28 Jul Shift 1) JEE Main Previous Year Paper is 330 m s-1.

Q25.In a potentiometer arrangement, a cell gives a balancing point at 75 cm length of wire. This cell is now replaced by another cell of unknown emf. If the ratio of the emf's of two cells respectively is 3 : 2 , the difference in the balancing length of the potentiometer wire in above two cases will be _____ cm.

Q25.A potentiometer wire of length 10 m and resistance 20 Ω is connected in series with a 25 V battery and an external resistance 30 Ω. A cell of emf E in secondary circuit is balanced by 250 cm long potentiometer wire. The value of E (in volt) is x . The value of x is _____ . 10 JEE Main 2022 (24 Jun Shift 2) JEE Main Previous Year Paper

Q25.A steam engine intakes 50 g of steam at 100°C per minute and cools it down to 20°C. If latent heat of vaporization of steam is 540 cal g-1, then the heat rejected by the steam engine per minute is _____ × 103 cal (Given : specific heat capacity of water : 1 cal g-1∘C-1)

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

Q26.The speed of a transverse wave passing through a string of length 50 cm and mass 10 g is 60 m s-1. The area of cross-section of the wire is 2 . 0 mm2 and its Young's modulus is 1 . 2 × 1011 N m-2. The extension of the wire over its natural length due to its tension will be x × 10-5 m. The value of 𝑥 is _____ .

Q26.For the network shown below, the value of VB −VA is _____ V . JEE Main 2022 (29 Jun Shift 1) JEE Main Previous Year Paper

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.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.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 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.An inductor of 0. 5 mH , a capacitor of 200 μF and a resistor of 2 Ω are connected in series with a 220 V ac source. If the current is in phase with the emf, the frequency of ac source will be ______ ×102 Hz .

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.A 10 Ω, 20 mH coil carrying constant current is connected to a battery of 20 V through a switch. Now after switch is opened current becomes zero in 100 μs. The average e.m.f. induced in the coil is _____ V.

Q26.As show in the figure, in steady state, the charge stored in the capacitor is _____ ×10−6C.

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 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.The potential energy of a particle of mass 4 kg in motion along the x-axis is given by U = 4(1 −cos 4x) J. The time period of the particle for small oscillation (sin θ ≃θ) ( Kπ ) s. The value of K is _____ .

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 first overtone frequency of an open organ pipe is equal to the fundamental frequency of a closed organ pipe. If the length of the closed organ pipe is 20 cm. The length of the open organ pipe is _____ cm

Q26.All resistances in figure are 1 Ω each. The value of current ' I ' is a5 A . The value of a is _____ .