CBSE [All India]-Set-2-2016

When a bar of diamagnetic material is placed in an external magnetic field, the field lines are repelled or expelled and the field inside the material is reduced.

Whereas when a paramagnetic material is placed in an external magnetic field, the field lines are attracted towards it. Thus the field lines get concentrated inside the material and the field inside is enhanced.

Let E and r be the EMF and internal resistance of all cells respectively and e and r' be the EMF and internal resistance of each cell respectively.

According to the definition of the terminal potential difference,

V = E − Ir

E is the EMF and r is the total internal resistance of the circuit.

I = 0 ⇒ V = E

From the graph we can see

E = 6 V

As there are three cells we can write,

E = 3 × e ⇒ e = 2 V

And, when, V = 0

⇒ E = Ir

As per the question the cells are connected in the series, so we can write.

At the time of sunset or sunrise, the Sun and its surroundings appear red because of the scattering of light. At the time of sunset or sunrise, the light rays from the Sun have to travel a long distance to reach our eyes through the Earth's atmosphere. In other words, we can say that when we look towards horizon, we are looking through more of Earth’s atmosphere than when we look overhead. The light reaching our eyes is rich in red colour as blue light is largely scattered away by the particles present in the Earth's atmosphere.

The net force on the charge q is directed parallel to the dipole and hence perpendicular to its motion along AB.

∴ Work done = 0

Communication is the act of transmission of information.

Communication system has three essential components − transmitter, medium channel, and receiver.

(a) According to the definition of terminal potential difference,

E = V + Ir

⇒ V = E – Ir

E = 12 V, r = 2 Ω

V = 12 – 2 I

When the voltmeter is connected across the cell,

I==2 A

V₁ = 12 – 2 (2) = 8 V

When the voltmeter is connected across the resistor,

V₂ = IR

= 2 × 4 = 8 V

V₁ = V₂

Hence, from the above relation we can see that voltmeter placed across the cell and across the resistor, gives the same reading.

(b) Voltmeter has very high resistance to ensure that its connection does not alter the flow of current in the circuit. We connect it in parallel and we also know that current chooses only the low resistance path. Hence, it is connected in parallel to the load across which potential difference is to be measured.

Ammeter measures value of current flowing through the circuit so it should be connected in the series. Ammeter has very low resistance to ensure that all the current flows through it. Thus, it gives a correct reading of the current when connected in series.

Ionization energy: The minimum amount of energy required to remove an electron from the outermost orbit of a neutral atom in its ground state is known as the ionization energy of that atom.

The ionization energy of Hydrogen atom is

E_H ∝ m_e .....(1)

When mass of electron is replaced by a particle having mass = 200m_e, then

E_H' ∝ 200m_e .....(2)

From (1) and (2), we have

E_H' = 200E_H = 200 × (−13.6) (∵ E_H=−13.6 eV)

= −2720 eV

Modulation index is defined as the ratio between amplitude of modulating signal and carrier wave.

As the low-frequency modulating signal is mixed with a high-frequency carrier wave, the distortion is restricted due to the high-frequency carrier wave for modulation index lying between 0 and 1. If the amplitude of modulating wave is greater than the carrier wave then the carrier wave gets over-modulated. This over modulation results in distorted waveform envelope which will result in a distorted output signal.

The bandpass filter blocks the signal which are d.c. or have frequencies ω, 2ω_c and 2ω_m and allows a particular band of frequency signal to pass.