25.4 Alternating Current & Power

A pure resistor is connected to an a.c. source where its current is given by I=5.0 sin 628t. Which of the following statements is not true about the circuit?

• The peak value of current flowing through the resistor is 5.0 A

• The root mean square current flowing through the resistor is 3.5 A

• The frequency of the current flowing through across the resistor is 120 Hz

• The equivalent direct current which gives the same average heating power in the resistor is 3.5 A

Find the ratio of  $\frac{mean\ power\ dissipated\ through\ R\ in\ \left(a\right)}{power\ dissipated\ through\ R\ in\ \left(b\right)}$  

• 2

•  $\frac{1}{2}$  

• 4

•  $\frac{1}{4}$  

The variation of voltage across an inductor with time t in an a.c. circuit is as shown in the graph. Which graphs shows the variation of the current I which flows through the inductor with time t?

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Tags

NGSS.HS-PS2-5

The r.m.s value of an alternating current is given by steady (D.C) current which when flowing through a given circuit for a given time produces

• the more heat than produced by A.C when flowing through the sam circuit

• the less heat than produced by A.C when flowing through the sam circuit

• the same heat than produced by A.C when flowing through the same circuit

A resistor is connected to an AC power supply. On this circuit, the current

• leads the voltage by 90°.

• lags the voltage by 90°.

• is in phase with the voltage.

• none of the given answers

Quantity of charge can be measured in

• time (s)

• Ampere (A)

• coulombs (C)

• Joule (J)

The function of a generator is to change ____. 

• mechanical energy to electrical energy
• electrical energy to mechanical energy 
• electrical energy to chemical energy
• chemical energy to electrical energy 

Tags

NGSS.HS-PS3-3

NGSS.HS-PS3-5

An electric current that continually reverses direction over time is known as a(n)?

• Alternating current

• direct current

• simple current

current is measured in?

• Volt

• ampere

• watt

The electricity in our house is?

• AC

• BC

• DC