Electric power Quiz 1

Question 1

Determine the amount of electric power supplied to the ice cream maker if the ice cream maker draws $$15\,A$$ of current when connected to a $$20\,V$$ power supply. How much operational heat does the ice cream maker generate if it takes $$15$$ minutes to churn out ice cream?

Accepted Answer

$$300\,W$$, $$0.075\,KWH$$

Answer

$$300\,W$$, $$0.75\,KWH$$

Answer

$$30\,W$$, $$0.75\,KWH$$

Answer

$$30\,W$$, $$0.075\,KWH$$

Question 2

A heat gun is a tool that emits a stream of hot air that is usually at temperatures between $$100^{\circ}C$$ and $$500^{\circ}C$$. The heat gun consists either of a gas flame or an electrical heating element and a fan to propel the hot air out. Suppose that you want to de-solder a few wires that you accidentally soldered into the wrong feedthrough on your circuit board, using a heat gun that is marked at $$1200\,W$$ and $$200\,V$$. If the heat gun is powered by a $$120\,V$$ supply voltage, determine the heat produced by it in $$5\,min$$.

Accepted Answer

$$130\,kJ$$

Answer

$$434\,kJ$$

Answer

$$564\,kJ$$

Answer

$$143\,kJ$$

Question 3

The following figure shows the cross section of the heating element used in a blowtorch. If the conductivity of nichrome is $$9.09 	imes 10^{5}\,Sm^{-1}$$ and that of constantan is $$2.04 	imes 10^{6}\,Sm^{-1}$$ and the rate at which heat is produced by constantan is $$Q$$, determine the rate at which heat is produced by nichrome. $$ \ $$  <img  src="https://cmds-vedantu.s3.ap-southeast-1.amazonaws.com/prod/question-sets/f996ea15-401f-4866-9ce4-a31ae3c8a6733266796675704289460.png"/>

Accepted Answer

$$8.98\,Q$$

Answer

$$2.64\,Q$$

Answer

$$3.96\,Q$$

Answer

$$0.6\,Q$$

Question 4

Let's presume your monthly home office energy bill is $$Rs.1200$$. You buy a new espresso machine and a minifridge for the office. If the espresso machine operates on a power of $$1000\,W$$ and is used on an average of $$15\,min$$ a day, and the minifridge that is kept switched on for $$16\,hours$$ a day operates at $$250\,W$$. If your local power station charges $$Rs.5$$ per $$kWh$$, then measure your total monthly electricity bill.

Accepted Answer

$$Rs.1837.5$$

Answer

$$Rs.1250.5$$

Answer

$$Rs.1221.25$$

Answer

$$Rs.2120.25$$

Question 5

Suppose that you just bought a glue gun for one of your crafts projects at home. The glue gun has two settings, one for low heat and one for high heat, and the rate at which heat is produced depends on the arrangement of the heating elements either in series or parallel in the glue gun. If one heating element can melt the glue in time $$t_1$$ and the other element can melt the same amount of glue in time $$t_2$$, determine the time taken for the glue gun to melt the glue when the heating elements are connected in series if they take time $$t_{p}$$ to melt the glue when connected in parallel.

Accepted Answer

$$\dfrac{t_1 t_2}{t_{p}}$$

Answer

$$\dfrac{t_{p}}{t_1+ t_2}$$

Answer

$$\dfrac{t_{p}}{t_1 t_2}$$

Answer

$$\dfrac{t_1+ t_2}{t_{p}}$$