For a given voltage four heating coils will produce max.

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For a given voltage four heating coils will produce max. heat when connected in—

1. All in parallel
2. All in series
3. With two parallel pairs in series
4. One pair in parallel with other two in series
5. A and C both

Correct Option: E

When all in parallel

heat produced, P =	V²
	R_eq

R _{e q} =	R
	4

or P =	4V²	....(i)
	R

(ii) When all in series

P =		V²	= 2√2	V²	.....(ii)
		R_eq		4R

(iii) With two parallel pairs in series

P = P₁ + P₂

=		V²	+	V²
		R_eq		R_eq

=		V²	+	V²	=	2V²	+	V²	=	5V²
		R/2		2R		R		2R		2R

(iv) One pair in parallel with other two in series

P = P₁ + P₂
= V² R/2 + V² 2R = 2V² R + V² 2R = 5V² 2R
From above discussion we see that heat in case (i) and (iii) is maximum so the alternative (A) and (C) are correct.