# Electrical Engineering - Energy and Power - Discussion

Discussion Forum : Energy and Power - General Questions (Q.No. 5)

5.

A power supply produces a 0.6 W output with an input of 0.7 W. Its percentage of efficiency is

Discussion:

30 comments Page 1 of 3.
AliBaBa said:
5 years ago

Why no one has manually solved this 0.6/0.7 to get 0.857.

06/10 Ã· 07/10.

06/10 * 10/07 cross multiplication will cancel both 10.

06/07 = 0.857,

For efficiency, %age multiply it with 100.

= 85.7%.

06/10 Ã· 07/10.

06/10 * 10/07 cross multiplication will cancel both 10.

06/07 = 0.857,

For efficiency, %age multiply it with 100.

= 85.7%.

(1)

Latjor said:
1 decade ago

Efficiency = Output / Input

= 0.6 / 0.7

= 0.857.

Than in percentage efficiency = 0.857 * 100

= 85.7 %.

= 0.6 / 0.7

= 0.857.

Than in percentage efficiency = 0.857 * 100

= 85.7 %.

Rani said:
10 years ago

Option D was correct because the efficiency will be calculated by using formula (output/input).

So,

0.6/0.7 = 0.857.

Under % = 85.7%

So,

0.6/0.7 = 0.857.

Under % = 85.7%

Ramakanth said:
1 decade ago

E = output/input =output/output+losses.

So in the question they have to give that losses are neglected.

Then the answer is correct.

So in the question they have to give that losses are neglected.

Then the answer is correct.

Elavendhan said:
1 decade ago

Efficiency(n) % = (Output Power / Input Power)*100

Efficiency(n) % = (0.6W / 0.7W)*100

Efficiency(n) % = 85.71

Efficiency(n) % = (0.6W / 0.7W)*100

Efficiency(n) % = 85.71

Dayu said:
5 years ago

eff=output power/input power * 100.

So output power is 0.6w and input power is 0.7 watt.

0.6/0.7 * 100 = 85.7%.

So output power is 0.6w and input power is 0.7 watt.

0.6/0.7 * 100 = 85.7%.

(4)

SANDYACHETHU said:
1 decade ago

Efficiency(n)=output/input

Efficiency(n)=0.6W/0.7W (BOTH "w" CANCEL)

n=0.8571

n%=0.8571x100

n=85.71%

Efficiency(n)=0.6W/0.7W (BOTH "w" CANCEL)

n=0.8571

n%=0.8571x100

n=85.71%

Ovii said:
1 decade ago

Adding to sandyachethu: ratio is always without units so thats why both 'w' would cancel eachother.

Ravi Purohit said:
1 decade ago

Because efficiency = output / input.

= 0.6 / 0.7 = 0.857 = 0.857*100 % = 85.7 %

= 0.6 / 0.7 = 0.857 = 0.857*100 % = 85.7 %

Sumathi said:
1 decade ago

Efficiency = Output/Input.

=0.6/0.7 = 0.857.

In Percentage, 0.857*100 = 85.7%.

=0.6/0.7 = 0.857.

In Percentage, 0.857*100 = 85.7%.

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