Question 10 - Past Year - 3 Mark Questions - Chapter 12 Class 10 - Electricity

A circuit has a line of 5 A. How many lamps of rating 40 W, 200 V can simultaneously run on this line safely?

Answer:

Given,

• Potential difference of one lamp, V = 200 V
• Power of each lamp, P = 40 W
• Total safe current, I = 5A 

Safe current through each lamp, 

i = P / V 

  = 40 / 200

  = 0.2 A

Therefore number of lamps that can be safely used,

n = I / i 

   = 5 / 0.2

    = 25