According to Ohm's law, at a constant temperature, the steady current 'I' flowing through a conductor is directly proportional to the potential difference 'V' between the two ends of the conductor.
\(I\alpha V \Rightarrow\)  V = IR

Electric potential : The electric potential at a point is defined as the amount of work done in moving a unit positive charge from infinity to that point against the electric force.
Electric potential difference : The electric potential difference between two points is defined as the amount of work done in moving a unit positive charge from one point to another point against the electric force.

A) Since the resistors are connected in parallel, the potential difference across each resistor is same (i.e. V=10V)
Therefore, the current through R₁ is,
\({ I }_{ 1 }=\frac { V }{ { R }_{ 1 } } =\frac { 10 }{ 5 } =2A\)
Current through \({ R }_{ 2 }={ I }_{ 2 }=\frac { V }{ { R }_{ 2 } } =\frac { 10 }{ 10 } =1A\)
Current through \({ R }_{ 3 }={ I }_{ 3 }=\frac { V }{ { R }_{ 3 } } =\frac { 10 }{ 20 } =0.5A\)
B) Total current in the circuit, I = I₁ + I₂ + I₃
= 2 + 1 + 0.5 = 3.5 A
C) Total resistance in the circuit  \(\frac { 1 }{ { R }_{ P } } =\frac { 1 }{ { R }_{ 1 } } +\frac { 1 }{ { R }_{ 2 } } +\frac { 1 }{ { R }_{ 3 } } \)
\(=\frac { 1 }{ 5 } +\frac { 1 }{ 10 } +\frac { 1 }{ 20 } \)
\(=\frac { 4+2+1 }{ 20 } \)
\(\frac { 1 }{ { R }_{ P } } =\frac { 7 }{ 20 } \)
Hence, \({ R }_{ P }=\frac { 20 }{ 7 } =2.857\Omega \) 

d) If the assertion is false but the reason is true.

c) If the assertion is true, but the reason is false.

(i) V = IR
(ii) H = I²Rt
(iii) R_s = R₁ + R₂
(iv) P = VI
(v) \(\rho=R\frac{A}{L}\)

(i) Electric heater.
(ii) Electric iron work on the heating effect of current.

(i) Resistance is inversely proportional to area of cross section. \(\mathbf{R} \alpha \frac{l}{A}\)
(ii) A thicker wire has Iarger area of cross section and hence the resistance decreases.

(i) The SI unit of current is ampere (A).
(ii) The current flowing through a conductor is said to be one ampere, when a charge of one coulomb flows across any cross-section of a conductor  in one second. 
\(1\ ampere=\cfrac { 1\ coulomb }{ 1\ second } \)

(a) Advantages of LED television:
(i) LED television has brighter picture quality
(ii) It is thinner in size
(iii) It uses less power and consumes very less energy.
(iv) Its life span is more.
(v) It is more reliable
(b) Merits of LED bulb:
(i) As there is no filament, there is no loss of energy in the form of heat. It is cooler than the incandescent bulbs
(ii) In comparison with the fluorescent light, the LED bulbs have significantly low power requirement.
(iii) It is not harmful to the environment
(iv) A wide range of colours is possible here.
(v) It is cost-efficient and energy efficient.
(vi) Mercury and other toxic materials are not required.
(vii) One way of overcoming the energy crisis is to use more LED bulbs.