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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 points)

Deadline expired on 10 February 2010.

Google Translation (Sorry, the solution is published in Hungarian only.)

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 on problem P. 4220.
 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

•  Támogatóink: Morgan Stanley