• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar

How Engineering Works

  • Home
  • About Us
  • Electrical Engineering
    • Interview Questions
  • Privacy Policy
  • Disclaimer
  • Contact Us
  • Blog

Electrical Questions

May 19, 2017 by admin

• Which bulb will glow brighter?

When a 60 W, 200 V bulb is connected in series with 100 W, 200 V bulb across a 200 V A.C. power supply, which bulb will glow brighter?

Solution: 60 Watt bulb will glow brighter then 100 Watt bulb.

Why ?
When two bulb are connected in series across a power supply, the voltage drop across each bulb depends upon its resistance value.

60 Watt power value is less than 100 Watt. Which means 60 watt bulb must have higher resistance value to resist the current flow.

Let us consider,
Resistance of 60 watt bulb = R1
Resistance of 100 watt bulb = R2

Therefore,     R1  >  R2

We know that,
Voltage drop, V = IR

As R1 is greater than R2, therefore voltage drop across 60 watt bulb is more than 100 watt bulb. Hence 60W bulb will consume more power and glow brighter.

In Short, the voltage drop across 60W bulb is more than 100W because 60W bulb has higher resistance. Hence 60W bulb will glow brighter.

 

• Find the total energy consumed (in joules) by bulb when it is ON for 6 hours?

When a 100 watt, 220 V bulb is connected across 220 V power supply. Find the total energy consumed by bulb when it is ON for 6 hours?

Solution: Given that
Power Rating (P) = 100 W
Supply Voltage (V) = 220 V
Energy consumed in 6 hours = ?

Formula used: 
Energy = Power  x  Time
Joule = Watt  x  Second

Convert 6 hours in seconds,
6 hours = 6 x 60 minutes x 60 second
6 hours = 21600 seconds

Now apply formula,
Energy = Power  x  Time
E = 100 x 21600
E = 2160000 joules
E = 2.16  x  106  Joules
Energy consume in kWh,
Energy = Power  x  Time
E = (100/1000) x  6
E = 0.6 kWh

In short, When a 100 watt, 220 V bulb is connected across 220 V power supply. It will consume 2.16  x  106  Joules of energy in six hours.

• What are the differences between fuse and circuit breaker?

Fuse
1. It is generally used in low voltage application.
2. It can detect and interrupt the fault.
3. Its work on the principle of electrical and thermal properties.
4. Operating time of fuse is very small.
5. Fuse element needs to replace after every operation.
6. Fuse cannot be used as an ON/OFF switch.

Circuit Breaker
1. Circuit breaker is suitable for high voltage application.
2. Circuit breaker cannot detect fault. It perform only interruptions and deductions of fault is made by relay.
3. Circuit breaker work on the electromagnetical principle.
4. Operating time of circuit breaker is higher as compared to fuse.
5. Circuit breaker can be used again and again after operation.
6. Circuit breaker can be used as an ON/OFF switch.


Also Read :

  • Why all the voltage levels are multiples of 11 kV? asked by Bahu
  • What is the function of a choke in tube light? asked by varu
  • What is the meaning of DYN11 in a transformer? asked by Hiter
  • What is the difference between Earthing and Grounding? asked by admin


INTERVIEW QUESTIONS

MCQ or Objective


Filed Under: Electrical Questions

Primary Sidebar


INTERVIEW QUESTIONS

MCQ or Objective


Recommended Post

Electrical Engineering Interview Questions

Electrical Engineering Questions

MCQs on Electrical Devices

Top Electricity Companies

Demo timer

Categories

  • Electrical Articles (19)
  • Electrical MCQ (75)
  • Electrical Questions (11)
  • Interviews Questions (7)
  • IQ Test (1)
  • Uncategorized (12)



Join Our Whatsapp Group


About Us | Privacy Policy | Disclaimer


Copyright@ Since-2017