LIVE Course for free

Rated by 1 million+ students
Get app now
0 votes
in Physics by (30.0k points)
closed by
A heater coil is cut into two equal parts and only one part is used in the heater. The heat generated now for the same current will be ________
1. Doubled
2. Four times
3. One fourth
4. Half

1 Answer

0 votes
by (30.0k points)
selected by
Best answer
Correct Answer - Option 1 : Doubled



  • The property of electrical materials and electrical instruments that opposes the flow of current through them is called resistance.
  • It is denoted by R. The SI unit of resistance is the ohm (Ω).
  • It is given as R = V / I

V is voltage or potential difference, I is the current.

  • Resistance is directly proportional to the length of the conductor. 

R ∝ l

Electric Power

Electric power is the rate of consumption of electric energy in any device. 

It is denoted as 

P = I2 R = V2 / R = V × I


In-home appliances, the potential difference is supplied at 220 V, 50 Hz. 

The connections are made in parallel. 

The average voltage is approximately maintained at this ratio. 


P = I2 R = V2 / R

\(\implies P ∝ \frac{1}{R}\)

So, Power is inversely proportional to resistance. 

P1R1 = P2R2

⇒ \(P_2 = P_1\frac{R_1}{R_2}\)    ---(1)

Since resistance is directly proportional to length, and 

R2 = R1 / 2   ---(2)

Now, putting (2) in (1) we get

P2 = 2 P1

So, the power is doubled. 

Why we haven't considered P = I2 R?

  • Since the current is not supplied to us. Potential difference is applied. 
  • All devices are connected in parallel, and they have same potential difference across them, not current. 

Welcome to Sarthaks eConnect: A unique platform where students can interact with teachers/experts/students to get solutions to their queries. Students (upto class 10+2) preparing for All Government Exams, CBSE Board Exam, ICSE Board Exam, State Board Exam, JEE (Mains+Advance) and NEET can ask questions from any subject and get quick answers by subject teachers/ experts/mentors/students.