Practice Questions

Q25.The threshold wavelength for photoelectric emission from a material is 5500 A . Photoelectrons will be emitted, when this material is illuminated with monochromatic radiation from a A. 75 W infra-red lamp B. 10 W infra-red lamp C. 75 W ultra-violet lamp D. 10 W ultra-violet lamp Choose the correct answer from the options given below : (1) B and C only (2) A and D only (3) C only (4) C and D only

Q25.The width of fringe is 2 mm on the screen in a double slit experiment for the light of wavelength of 400 nm. The width of the fringe for the light of wavelength 600 nm will be: (1) 4 mm (2) 2 mm (3) 1. 33 mm (4) 3 mm

Q25.When one light ray is reflected from a plane mirror with 30° angle of reflection, the angle of deviation of the ray after reflection is: JEE Main 2023 (11 Apr Shift 2) JEE Main Previous Year Paper (1) 120° (2) 110° (3) 140° (4) 130°

Q25.The difference between threshold wavelengths for two metal surfaces A and B having work function ϕA = 9 eV and ϕB = 4. 5 eV in nm is: {Given, hc = 1242 eV nm } (1) 540 (2) 276 (3) 264 (4) 138

Q25.The equation of wave is given by 𝑌= 10-2sin2𝜋160𝑡- 0 . 5𝑥+ 4, where 𝑥 and 𝑌 are in 𝑚 and 𝑡 in 𝑠. The speed of the wave is _______ km h-1.

Q26.In an experiment to find emf of a cell using potentiometer, the length of null point for a cell of emf 1 . 5 V is found to be 60 cm. If this cell is replaced by another cell of emf 𝐸. the length-of null point increases by 𝑥 40 cm. The value of 𝐸 is V. The value of 𝑥 is ______. 10

Q26.Electron beam used in an electron microscope, when accelerated by a voltage of 20 kV has a de-Broglie wavelength of λ0 . If the voltage is increased to 40 kV then the de-Broglie wavelength associated with the electron beam would be: (1) 3λ0 (2) 9λ0 (3) λ0 (4) λ0 2 √2

Q26.If a radioactive element having half-life of 30 min is undergoing beta decay, the fraction of radioactive element remains undecayed after 90 min will be : (1) 1 (2) 1 8 16 (3) 1 (4) 1 4 2

Q26.Proton (P) and electron (e) will have same de-Broglie wavelength when the ratio of their momentum is (assume, mp = 1849 me ) (1) 1 : 1 (2) 1 : 1849 (3) 1 : 43 (4) 43 : 1

Q26.The light rays from an object have been reflected towards an observer from a standard flat mirror, the image observed by the observer are :- A. Real B. Erect C. Smaller in size than object D. Laterally inverted Choose the most appropriate answer from the options given below: (1) B and D only (2) B and C only (3) A and D only (4) A, C and D only

Q27.The current required to be passed through a solenoid of 15 cm length and 60 turns in order to demagnetise a bar magnet of magnetic intensity 2 . 4 × 103 A m – 1 is ________ A.

Q27.The radius of electron's second stationary orbit in Bohr's atom is R. The radius of 3rd orbit will be (1) R (2) 2. 25 R 3 (3) 3R (4) 9R

Q27.An electron of a hydrogen like atom, having Z = 4 , jumps from 4th energy state to 2nd energy state, The energy released in this process, will be: (Given Rch = 13. 6 eV ) Where R = Rydberg constant c = Speed of light in vacuum h = Planck's constant (1) 13. 6 eV (2) 10. 5 eV (3) 3. 4 eV (4) 40. 8 eV

Q28.For the following circuit and given inputs A and B, choose the correct option for output ‵Y ′ JEE Main 2023 (13 Apr Shift 1) JEE Main Previous Year Paper (1) (2) (3) (4)

Q28.Which of the following statement is not correct in the case of light emitting diodes? A. It is a heavily doped p-n junction. B. It emits light only when it is forward biased. C. It emits light only when it is reverse biased. D. The energy of the light emitted is equal to or slightly less than the energy gap of the semiconductor used. Choose the correct answer from the options given below : (1) C and D (2) A (3) C (4) B

Q28.The energy of He+ ion in its first state is, (The ground state energy for the Hydrogen atom −13. 6 eV): (1) −27. 2 eV (2) −3. 4 eV (3) −13. 6 eV (4) −54. 4 eV

Q28.For the given logic gates combination, the correct truth table will be (1) A B X (2) A B X 0 0 1 0 0 0 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 0 (3) A B X (4) A B X 0 0 1 0 0 0 0 1 0 0 1 1 1 0 1 1 0 1 1 1 0 1 1 1

Q28.The ratio of the density of oxygen nucleus (168O) and helium nucleus (42He) is (1) 4 : 1 (2) 8 : 1 (3) 1 : 1 (4) 2 : 1

Q28.The work functions of Aluminium and Gold are 4. 1 eV and 5. 1 eV respectively. The ratio of the slope of the stopping potential versus frequency plot for Gold to that of Aluminium is (1) 1. 24 (2) 2 (3) 1 (4) 1. 5

Q29.The modulation index for an A.M. wave having maximum and minimum peak to peak voltages of 14 mV and 6 mV respectively is : (1) 1. 4 (2) 0. 4 (3) 0. 2 (4) 0. 6

Q29.If the height of transmitting and receiving antennas are 80 m each, the maximum line of sight distance will be : Given : Earth’s radius = 6. 4 × 106 m . (1) 32 km (2) 28 km (3) 36 km (4) 64 km

Q29.Choose the correct statement about Zener diode: (1) It works as a voltage regulator in reverse bias and (2) It works as a voltage regulator in both forward behaves like simple p-n junction diode in forward and reverse bias bias (3) It works a voltage regulator only in forward bias (4) It works as a voltage regulator in forward bias and behaves like simple p-n junction diode in reverse bias

Q29.In an n-p-n common emitter (CE) transistor the collector current changes from 5 mA to 16 mA for the change in base current from 100 μA and 200 μA, respectively. The current gain of transistor is _____. (1) 110 (2) 210 (3) 0. 9 (4) 9

Q30.In satellite communication, the uplink frequency band used is: (1) 420 −890 MHz (2) 5. 925 −6. 425 GHz (3) 76 −88 MHz (4) 3. 7 −4. 2 GHz

Q30.A message signal of frequency 5 kHz is used to modulate a carrier signal of frequency 2 MHz . The bandwidth for amplitude modulation is: (1) 5 kHz (2) 20 kHz (3) 10 kHz (4) 2. 5 kHz