Mathematical and Physical Journal
for High Schools
Issued by the MATFUND Foundation
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# Problem P. 4220. (January 2010)

P. 4220. An immersion heater is rated at 350 W when it is run on a sinusoidal electricity supply of voltage 230 V.

a) What is the smallest and the greatest instantaneous power of the immersion heater when it is operating?

b) What is the maximum value of the instantaneous current that flows through the heater?

c) Why is it not allowed to turn on the heater before immersing it into the water?

(3 pont)

Deadline expired on February 10, 2010.

Sorry, the solution is available only in Hungarian. Google translation

Megoldás. $\displaystyle a.)$ $\displaystyle P^{\rm pill}_{\rm min}=0$ W és $\displaystyle P^{\rm pill}_{\rm max}=700$ W

$\displaystyle b.)$ $\displaystyle I_{\rm max}=2{,}15$ A.

$\displaystyle c.)$ Mert gyorsan túlmelegedne és leégne a fűtőszál.

### Statistics:

 89 students sent a solution. 3 points: 56 students. 2 points: 17 students. 1 point: 12 students. Unfair, not evaluated: 4 solutions.

Problems in Physics of KöMaL, January 2010