Question

what is the highest and lowest total resistance that can be secured by combination of four coils of resistance 5ohm,10ohm,15ohm and 20ohm..
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Answer 1

Answer:

A Circuit has maximum resistance when resistors are connected in series pattern and a Circuit has minimum resistance when resistors are connected in parallel pattern .

Explanation:

FOR MAXIMUM RESISTANCE

$R max= R1+ R2+R3....+Rn\\R max= 5+10+15+20\\R max= 50 ohm\\\\\frac{1}{R}min =\frac{1}{5} + \frac{1}{10}+ \frac{1}{15}+ \frac{1}{20} \\\\\frac{1}{R} min= \frac{ 12+6+4+3}{60} =\frac{25}{60} \\\\R min= \frac{60}{25} ohm= 2.4 ohm$