## NCERT Solutions for Class 12 Physics Chapter 4 – Atoms

Question 12.1: Choose the correct alternative from the clues given at the end of the each statement: (a) The size of the atom in Thomson’s model is ………. the atomic size in Rutherford’s model. (much greater than/no different from/much less than.) (b) In the ground state of ………. electrons are in stable equilibrium, while in ………. electrons …

## NCERT Solutions for Class 12 Physics Chapter 11 – Dual Nature Of Radiation And Matter

Question 11.1: Find the (a) maximum frequency, and (b) minimum wavelength of X-rays produced by 30 kV electrons. Answer: Potential of the electrons, V = 30 kV = 3 × 104 V Hence, energy of the electrons, E = 3 × 104 eV Where, e = Charge on an electron = 1.6 × 10−19 C (a)Maximum frequency produced by the X-rays = ν The energy of …

## NCERT Solutions for Class 12 Physics Chapter 10 – Wave Optics

Question 10.1: Monochromatic light of wavelength 589 nm is incident from air on a water surface. What are the wavelength, frequency and speed of (a) reflected, and (b) refracted light? Refractive index of water is 1.33. Answer: Wavelength of incident monochromatic light, λ = 589 nm = 589 × 10−9 m Speed of light in air, c = …

## NCERT Solutions for Class 12 Physics Chapter 9 – Ray Optics And Optical Instruments

Question 9.1: A small candle, 2.5 cm in size is placed at 27 cm in front of a concave mirror of radius of curvature 36 cm. At what distance from the mirror should a screen be placed in order to obtain a sharp image? Describe the nature and size of the image. If the candle …

## NCERT Solutions for Class 12 Physics Chapter 8 – Electromagnetic Waves

Question 8.1: Figure 8.6 shows a capacitor made of two circular plates each of radius 12 cm and separated by 5.0 cm. The capacitor is being charged by an external source (not shown in the figure). The charging current is constant and equal to 0.15 A. (a) Calculate the capacitance and the rate of charge of …

## NCERT Solutions for Class 12 Physics Chapter 7 – Alternating Current

Question 7.1: A 100 Ω resistor is connected to a 220 V, 50 Hz ac supply. (a) What is the rms value of current in the circuit? (b) What is the net power consumed over a full cycle? Answer: Resistance of the resistor, R = 100 Ω Supply voltage, V = 220 V Frequency, ν = 50 Hz (a) The rms value of current in …

## NCERT Solutions for Class 12 Physics Chapter 6 – Electromagnetic Induction

Question 6.1: Predict the direction of induced current in the situations described by the following Figs. 6.18(a) to (f ). (a) (b) (c) (d) (e) (f) Answer: The direction of the induced current in a closed loop is given by Lenz’s law. The given pairs of figures show the direction of the induced current when …

## NCERT Solutions for Class 12 Physics Chapter 5 – Magnetism And Matter

Question 5.1: Answer the following questions regarding earth’s magnetism: (a) A vector needs three quantities for its specification. Name the three independent quantities conventionally used to specify the earth’s magnetic field. (b) The angle of dip at a location in southern India is about 18º. Would you expect a greater or smaller dip angle in Britain? (c) If …