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ꜱᴛᴀᴛᴇ ᴀɴᴅ ᴅᴇʀɪᴠᴇ ᴊᴏᴜʟᴇ’ꜱ ʟᴀᴡ. ᴀɴ ᴇʟᴇᴄᴛʀɪᴄ ɪʀᴏɴ ᴄᴏɴꜱᴜᴍᴇꜱ ᴇɴᴇʀɢʏ ᴀᴛ ʀᴀᴛᴇ ᴏꜰ 420ᴡ ᴡʜᴇɴ ʜᴇᴀᴛɪɴɢ ɪꜱ ᴀᴛ ᴍᴀxɪᴍᴜᴍ ʀᴀᴛᴇ ᴀɴᴅ 180 ᴡ ᴡʜᴇɴ ʜᴇᴀᴛɪɴɢ ɪꜱ ᴀᴛ ᴍɪɴɪᴍᴜᴍ. ᴛʜᴇ ᴠᴏʟᴛᴀɢᴇ ɪꜱ 220ᴠ .ᴡʜᴀᴛ ɪꜱ ᴛʜᴇ ᴄᴜʀʀᴇɴᴛ ᴀɴᴅ ʀᴇꜱɪꜱᴛᴀɴᴛ ɪɴ ᴇᴀᴄʜ ᴄᴀꜱᴇ?




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⚡Qᴜᴀʟɪᴛʏ ᴀɴꜱᴡᴇʀ ɴᴇᴇᴅᴇᴅ⚡


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Answer 1

Answer:

hey here is your solution

pls mark it as brainliest

joules law of heating expression is in above pics

Explanation:

$so \: here \: for \: an \: electric \: iron \\ power \: (P1) = 420.W \\ power \: (P2) = 180.W \\ common \: voltage \: (V) = 220.V \\ \\ so \: we \: know \: that \\ power = voltage \times current \: \\ hence \: accordingly \\ P1 = V.I1 \\ 420 = 220.I1 \\ = \frac{420}{220} \\ \\ = \frac{42}{22} \\ \\ = \frac{21}{11} \\ \\ hence \: I1 = \frac{21}{11} A$

$similarly \: \\ P2 = V.I2 \\ 180 = 220.I2 \\ = \frac{180}{220} \\ \\ = \frac{18}{22} \\ \\ = \frac{9}{11} \\ \\ hence \: I2 = \frac{9}{11} A$

$for \: finding \: resistance \: use \: ohms \: law \: ie \: V=IR$

Answer 2

Short Answer:

Joule's law of heating => H = I²Rt

When heating is maximum:

• I = 1.909 A
• R = 115.24 Ω

When heating is minimum:

• I = 0.818 A
• R = 268.94 Ω

Explanation:

State and derive Joule's law:

Joule's law of heating states that Heat generated is equal to the current multiplied by square of resistance and time.

Mathematically,

【H = I²Rt】

Derivation:

We know that:

W = V × Q ----- [Equation 1]

where:

• W = Work done
• V = Voltage
• Q = Charge

Also,

Q = It ----- [Equation 2]

From Ohm's law,

V = I × R ------ [Equation 3]

Put the values of V and Q from Equation 2 and Equation 3 in Equation 1.

W = V × Q

→ W = I × R × I × t

→ W = I²Rt

Here, work done = Heat produced.

So H = I²Rt

Next part of the question:

An electric iron consumes energy at rate of 420 W when heating is at maximum and 180 W when heating is at minimum. The voltage is 220 V. What is the current and resistance in each case?

Solution:

When heating is maximum:

• P = 420 W
• V = 220 V

I = P ÷ V

→ I = 420 ÷ 220

→ 『I = 1.909 A』

R = V ÷ I (Ohm's law)

→ R = 220 ÷ 1.909

→ 『R = 115.24 Ω』

When heating is minimum:

• P = 180 W
• V = 220 V

I = P ÷ V

→ I = 180 ÷ 220

→ 『I = 0.818 A』

Again by Ohm's law

R = V ÷ I

→ R = 220 ÷ 0.818

→ 『R = 268.94 Ω』