Joule's Heating Effect and Power :
When a current `I` flows for time `t` from a source of emf `E`, then the amount of charge that flows in time `t` is `Q = I t` .
Electrical energy delivered `W = Q. V = V I t`
Thus, Power given to the circuit, `= W//t =VI` or `V^2//R` or `I^2R`
In the circuit
`E*I = I^2R + I^2r`, where `E I` is the rate at which chemical energy is converted to electrical energy, `I^2R` is power supplied to the external resistance `R` and `I^2r` is the power dissipated in the internal resistance of the battery. An electrical current
flowing through conductor produces heat in it. This is known as Joule's heating effect. The heat developed in Joules is given by `H = I^2*R*t`
Heating effect of electric current
The heat which is produced due to the flow of current within an electric wire, is expressed in Joules. Now the mathematical representation or explanation of Joule-s law is given in the following manner
(a) Law of current
The amount of heat produced in current conducting wire, is proportional to the square of the amount of current that is flowing through the circuit, when the electrical resistance of the wire and the time of current flow is constant.
i.e. `H ∝ i^2` (When R & t are constant)
This verifies the law of electric current.
(b) Law of time (R and i kept constant)
Let `H_1` and `H_2` be the amounts of heat produced when a current -i- flows through the same resistance R for times t1 and t2 respectively. Experimentally, it is observed that,
`H_1/H_2 = t_1/t_2`
indicating that `H ∝ t.`
(c) Law of resistance (i and t kept constant)
Let `H_1` be the amount of heat produced when an electric current `i` flows through a wire of resistance `R_1` for a time -t-. Replace the wire by another wire of resistance `R_2` Let `H_2` be the heat produced when same current passes through it for same time.
Experimentally, it is observed that, `H_1/H_2 = R_1/R_2`
indicating that `H ∝ R.`
This verifies the law of resistance.
While stating Joule-s law, we should be clear about the quantity which is maintained constant.
(i) When current is kept constant,
`H ∝ i^2`
`H ∝ R`
`H ∝ t`
(ii) When potential difference is kept constant,
`H ∝ V^2`
`H ∝ 1/R`
`H ∝ t`
Electrical energy delivered `W = Q. V = V I t`
Thus, Power given to the circuit, `= W//t =VI` or `V^2//R` or `I^2R`
In the circuit
`E*I = I^2R + I^2r`, where `E I` is the rate at which chemical energy is converted to electrical energy, `I^2R` is power supplied to the external resistance `R` and `I^2r` is the power dissipated in the internal resistance of the battery. An electrical current
flowing through conductor produces heat in it. This is known as Joule's heating effect. The heat developed in Joules is given by `H = I^2*R*t`
Heating effect of electric current
The heat which is produced due to the flow of current within an electric wire, is expressed in Joules. Now the mathematical representation or explanation of Joule-s law is given in the following manner
(a) Law of current
The amount of heat produced in current conducting wire, is proportional to the square of the amount of current that is flowing through the circuit, when the electrical resistance of the wire and the time of current flow is constant.
i.e. `H ∝ i^2` (When R & t are constant)
This verifies the law of electric current.
(b) Law of time (R and i kept constant)
Let `H_1` and `H_2` be the amounts of heat produced when a current -i- flows through the same resistance R for times t1 and t2 respectively. Experimentally, it is observed that,
`H_1/H_2 = t_1/t_2`
indicating that `H ∝ t.`
(c) Law of resistance (i and t kept constant)
Let `H_1` be the amount of heat produced when an electric current `i` flows through a wire of resistance `R_1` for a time -t-. Replace the wire by another wire of resistance `R_2` Let `H_2` be the heat produced when same current passes through it for same time.
Experimentally, it is observed that, `H_1/H_2 = R_1/R_2`
indicating that `H ∝ R.`
This verifies the law of resistance.
While stating Joule-s law, we should be clear about the quantity which is maintained constant.
(i) When current is kept constant,
`H ∝ i^2`
`H ∝ R`
`H ∝ t`
(ii) When potential difference is kept constant,
`H ∝ V^2`
`H ∝ 1/R`
`H ∝ t`