For getting a sharp image, we have to use light of suitable wavelength. This is because focal length of a lens depends upon wavelength.

\(\beta =\cfrac { D\lambda }{ d } ,i.e\beta \propto \lambda \)  the wavelength of blue light is less than that of red light, hence if red light is replaced by blue light, the fringe width decreases, i.e., fringes come closer.

Dispersion is splitting of white light into its constituent colours. This band of colours of lightis called its spectrum.

(i) Light must travel from denser to rarer medium,
(ii) Angle of incidence in the denser medium must be greater than critical angle (i > i_c).

As photo current is proportional to intensity of incident light, the photocurrent will be doubled; but the maximum kinetic energy of emitted photoelectrons does not depend upon the intensity of incident light; hence the maximum kinetic energy remains unchanged.

Maximum kinetic energy, (E_k)_max = eVs = e(2V) = 2eV

(i) Top - down approach.
(ii) Bottom - up approach.

(i) Water repellant nano paints are made.
(ii) Coating with such nano paints give durability, protection against stains and dirt also enhances fuel efficiency when coated on ships.

In ground wave propagation, the energy of the signal is absorbed by the earth. The loss of energy increases with the increases in the frequency of the signal. So it is not suitable for high frequency.

The voltage at which the diode breaks down is called the breakdown voltage

The process in which alternating voltage or alternating current is converted direct voltage or direct current is called rectification.

When the hydrogen is burnt out, the sun will enter into a new phase called the red giant where helium will fuse to become carbon. During this stage, the sun will expand greatly in size and all its planets will be engulfed in it

(i) During charging or discharging there is a displacement current, but no conduction current between the plates of the capacitor.
(ii) The displacement current is equal to conduction current I_d = I_c, so I_d = 0.25 A.

(i) After disconnecting the battery, the charge on capacitor remains constant.
∴ energy stored capacitor \(\left( U=\frac { { q }^{ 2 } }{ 2C } \right) \)
(ii) As the battery remains connected, the potential difference remains constant.
Hence energy stored U = \(\frac{1}{2}\) CV² decreases.

The material having +ve and small susceptibility is paramagnetic material.
(i) They have a tendency to move from weaker to stranger parts of the field.
(ii) Susceptibility is inversely proportional to the temperature.

There are three quantities required to specify the magnetic field of the earth on its surface, which are often called as the elements of the earth's magnetic field. they are
(a) Magnetic declination (D)
(b) Magnetic dip or inclination (I)
(c) the horizontal component of the Earth's magnetic field (B_H)

The current in an a.c circuit is waltless if the average power consumed in the circuit is zero.

RLC circuits have many applications like filter circuits, oscillators, voltage multipliers, etc. An important use of series RLC resonant circuits is in the tuning circuits of radio and TV systems.

(i) To increase the resistance of the circuit the resistor are connected in series.
(ii) When they are connected in parallel resistance of the circuit is decreased

It consists of a tungsten filament (melting point 3380^oC) kept inside a glass bulb with inert gas maintained at low pressure and heated to incandescence by the current. Electric discharge lamps, electric welding and electric arc also utilize the heating effect of current.

The electrical power P is the rate at which the electrical potential energy is delivered
\(P=\cfrac { dW }{ dt } =\cfrac { d }{ dt } \left( V.dQ \right) =V\cfrac { dQ }{ dt } \)
Since the electric current \(I=\cfrac { dQ }{ dt } \).
So the equation (1) can be rewritten as P = VI
This expression gives the power delivered by the battery to any electrical system, where I is the current passing through it and V is the potential difference across it. The SI unit of electrical power is a watt.

(i) When d battery is disconnected, the capacitance increase from C₀ to C
(ii) New potential difference between the plates
\(V=\frac { { Q }_{ 0 } }{ C } =\frac { { C }_{ 0 }{ V }_{ 0 } }{ C } =\frac { { C }_{ 0 }{ V }_{ 0 } }{ { \varepsilon }_{ r }{ C }_{ 0 } } =\frac { { V }_{ 0 } }{ { \varepsilon }_{ r } } \)

(i) At a distance r; the force on the small sphere due to large sphere
\(F=\frac { 1 }{ 4\pi { \varepsilon }_{ 0 } } .\frac { Qq }{ { mr }^{ 2 } } \)
(ii) If m is the mass of small sphere then its acceleration
\(a=\frac { F }{ m } =\frac { 1 }{ 4\pi { \varepsilon }_{ 0 } } .\frac { Qq }{ { mr }^{ 2 } } \)
(iii) As the small sphere is pushed away (i.e. r increased) 'a' decrease.
(iv) As 'a' is always +ve the speed of the small sphere goes on increasing.
(v) ∴ increasing velocity and decreasing acceleration.
(d) is correct

The average time between successive collisions is called the mean free time denoted by \(\tau \)

When an external electric field is applied, the dipoles inside the polar molecule tend to align in the direction of the electric field. Hence a net dipole moment is induced in it. Then the dielectric is said to be polarized by an external electric field.

It is defined as the deflection produced per unit current flowing through the galvanometer.
I_s  = \(\frac { \theta }{ I } =\frac { NAB }{ K } \Rightarrow I_{ s }=\frac { I }{ G } \).

The magnitude of the reverse magnetising field for which the residual magnetism of the material vanishes is called its coercivity.