a bulb of 100W and anather bulb of 200W , rated supply
voltage 230v.when supply voltage is reduced to 100v,which
bulb will give more light? and why with calculation?

Answers were Sorted based on User's Feedback



a bulb of 100W and anather bulb of 200W , rated supply voltage 230v.when supply voltage is reduced..

Answer / nimish

P = V*i

For 100w bulb i = 100/230 = 0.4 A

For 200w bulb i = 200/230 = 0.8 A

Now voltage is reduced to 100 V , i = 100 / 100 = 1 A

i = 200 / 100 = 2 A

So, 200 W bulb will give more light.

Is This Answer Correct ?    63 Yes 10 No

a bulb of 100W and anather bulb of 200W , rated supply voltage 230v.when supply voltage is reduced..

Answer / glen

THE CURRENT CONSUMED BY 200W
I=.86A
RESISTANCE=268

THE CURRENT CONSUMED BY 100W
I=.43
R=535


IF VOLTAGE IS REDUCED THEN
FOR 200W
I=V/R=100/268=0.374A
FOR 100W
I=0.186A

THEREFORE 200W LAMP WILL GLOW MORE AS COMPARED TO 100W

Is This Answer Correct ?    18 Yes 8 No

a bulb of 100W and anather bulb of 200W , rated supply voltage 230v.when supply voltage is reduced..

Answer / nitin

p=v^2/r
now in both cases whtevr the voltage ,it is same for both
bulbs.
now the main culprit is r,the bulb which has more
resistance would glow dimmer as per above formula.
we have used the above formula bcaz ,elctrcl instruments
are designd for constant voltage.
as power is inversely proportonal to the resistance (above
formula)therefor 200w bulb would have less resistance and
glow more

Is This Answer Correct ?    13 Yes 6 No

a bulb of 100W and anather bulb of 200W , rated supply voltage 230v.when supply voltage is reduced..

Answer / pillay

If the illuminating efficiency of the filament is directly propotional to the current flow than I belive the answers that say the 200 watt bulb will glow brighter than the 100 watt bulb at 100 volts

Is This Answer Correct ?    8 Yes 4 No

a bulb of 100W and anather bulb of 200W , rated supply voltage 230v.when supply voltage is reduced..

Answer / skimatix

At 230V a 100W bulb will draw ~ 434mA
At 230V a 200W bulb will draw ~ 869mA

By reducing the voltage the current will rise, P = VI.

At 100V a 100W bulb will draw = 1A
At 100V a 200W bulb will draw = 2A

Is This Answer Correct ?    6 Yes 3 No

a bulb of 100W and anather bulb of 200W , rated supply voltage 230v.when supply voltage is reduced..

Answer / sibtain

the brightness of the bulb is depend on its resistance.its
totally wrong to say that bulb will fuse.in our life when
electricity is dim are you ever seen that bulb will burn? no

Is This Answer Correct ?    3 Yes 2 No

a bulb of 100W and anather bulb of 200W , rated supply voltage 230v.when supply voltage is reduced..

Answer / mohit goyal

if both are connected in series. so 100w lamp more bright because its resistance is high so voltage drop is high in case of series. current is same both lamp.

if both r connected in parallel. so 200w lamp more bright because in case of parallel. voltage across each lamp is same so 200w lamp more bright.

Is This Answer Correct ?    3 Yes 2 No

a bulb of 100W and anather bulb of 200W , rated supply voltage 230v.when supply voltage is reduced..

Answer / dilip

If we operate a 230V rated bulb on 100V the current will be
almost 2.5 time more than the 230V. So both bulbs will be
fused and none of it will glow.
P = V*i

For 100w bulb i = 100/230 = 0.4 A

For 200w bulb i = 200/230 = 0.8 A

Now voltage is reduced to 100 V , i = 100 / 100 = 1 A

i = 200 / 100 = 2 A

If we operate a 230V rated bulb on 100V the current will be
two time more than the 230V. So both bulbs will be fused
and none of it will glow.

Is This Answer Correct ?    10 Yes 11 No

a bulb of 100W and anather bulb of 200W , rated supply voltage 230v.when supply voltage is reduced..

Answer / vasanth

100w bulb will give more light
due to p=v*i, i=v/r.
calculate R value
lighting will related to heat loss
calculate heat generated /100 volt

Is This Answer Correct ?    13 Yes 15 No

a bulb of 100W and anather bulb of 200W , rated supply voltage 230v.when supply voltage is reduced..

Answer / pradeep.b

General guid : If voltage reduces then current increases.

A 230 volts rated Bulb can't be operated on 100volts
becuase, when you starts operating a 230 volts rated bulb
in 100 volts, the current increases between 2 to 2.5 times.

Is This Answer Correct ?    2 Yes 5 No

Post New Answer

More Electrical Engineering Interview Questions

In an ideal transformer no load primary current I0 A lags behind V1 by 90 degree B is in the phase with V1 C leads V1 by 90 degree D lags V1 by 45 degree

1 Answers  


why not feeling shock while touching rotor shaft of induction motor during running condition? during running condition emf induced in rotor.

1 Answers  


what material is the electrical housing wire made of? is there any difference for the telephone lines?

0 Answers  


What is the minimum value of hfe for the oscillations in transistorized rc phase shift oscillator?

0 Answers  


Reduction in supply voltage by 10% will change the torque of the motor by ___.

1 Answers   UGVCL Uttar Gujarat Vij Company Ltd,






what are the installation procedure of high voltage power transformer,CT,CB&PT?

0 Answers   Siemens,


how can calculate resistance box for 15 kw, 6 pole, RV-230, RA-42 motor

0 Answers  


how motor should be connected i.e star-delta or star-star or delta-delta ?

3 Answers   GSE,


CAN 50Hz transformer work at 60 Hz power supply? if yes how it is possible?

2 Answers  


Graphs of measuring power and speed on dc motor

0 Answers  


If two induction motors A and B are identical except that the air-gap motor 'A' is 50 % greater than that of motor 'B', then

2 Answers   Lanco,


can u light up bulb with out useing neutral

12 Answers  


Categories
  • Civil Engineering Interview Questions Civil Engineering (5085)
  • Mechanical Engineering Interview Questions Mechanical Engineering (4451)
  • Electrical Engineering Interview Questions Electrical Engineering (16632)
  • Electronics Communications Interview Questions Electronics Communications (3918)
  • Chemical Engineering Interview Questions Chemical Engineering (1095)
  • Aeronautical Engineering Interview Questions Aeronautical Engineering (239)
  • Bio Engineering Interview Questions Bio Engineering (96)
  • Metallurgy Interview Questions Metallurgy (361)
  • Industrial Engineering Interview Questions Industrial Engineering (259)
  • Instrumentation Interview Questions Instrumentation (3014)
  • Automobile Engineering Interview Questions Automobile Engineering (332)
  • Mechatronics Engineering Interview Questions Mechatronics Engineering (97)
  • Marine Engineering Interview Questions Marine Engineering (124)
  • Power Plant Engineering Interview Questions Power Plant Engineering (172)
  • Textile Engineering Interview Questions Textile Engineering (575)
  • Production Engineering Interview Questions Production Engineering (25)
  • Satellite Systems Engineering Interview Questions Satellite Systems Engineering (106)
  • Engineering AllOther Interview Questions Engineering AllOther (1379)