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.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 composite parallel plate capacitor is made up of two different dielectric materials with different thickness ( t1 and t2 ) as shown in figure. The two different dielectric material are separated by a conducting foil F . The voltage of the conducting foil is _____ V .

Q25.An ideal fluid of density 800 kg m−3 , flows smoothly through a bent pipe (as shown in figure) that tapers in cross-sectional area from a to a . The pressure difference between the wide and narrow sections of pipe is 2 4100 Pa . At wider section, the velocity of fluid is √x6 m s−1 for x = _____ . (Given g = 10 m s−2 )

Q25.The variation of applied potential and current flowing through a given wire is shown in figure. The length of wire is 31. 4 cm. The diameter of wire is measured as 2. 4 cm. The resistivity of the given wire is measured as x × 10−3 Ω cm. The value of x is _____ . [Take π = 3. 14 ]

Q25.The metallic bob of simple pendulum has the relative density 5. The time period of this pendulum is 10 s. If the metallic bob is immersed in water, then the new time period becomes 5√𝑥 s. The value of 𝑥 will be _____ .

Q25.A heat engine operates with the cold reservoir at temperature 324 K. The minimum temperature of the hot reservoir, if the heat engine takes 300 J heat from the hot reservoir and delivers 180 J heat to the cold reservoir per cycle, is _____ K .

Q25.Two resistors are connected in series across a battery as shown in figure. If a voltmeter of resistance 2000 Ω is used to measure the potential difference across 500 Ω resister, the reading of the voltmeter will be _____ V

Q25.Three point charges of magnitude 5 𝜇C, 0 . 16 𝜇C and 0 . 3 𝜇C are located at the vertices 𝐴, 𝐵, 𝐶 of a right angled triangle whose sides are 𝐴𝐵= 3 cm, 𝐵𝐶= 3√2 cm and 𝐶𝐴= 3 cm and point 𝐴 is the right angle corner. Charge at point 𝐴 experiences _____ N of electrostatic force due to the other two charges.

Q25.A 1 m long copper wire carries a current of 1 A . If the cross section of the wire is 2. 0 mm2 and the resistivity of copper is 1. 7 × 10−8 Ω m. The force experienced by moving electron in the wire is _____ ×10−23 N (Charge of electron = 1. 6 × 10−19C )

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.As shown in the figure an inductor of inductance 200 mH is connected to an AC source of emf 220 V and frequency 50 Hz. The instantaneous voltage of the source is 0 V when the peak value of current is √aπ A . The value of a is _____ .

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

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

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