Question

help me how you deduce the answer. what is the exact formula for this?

Answer 1

@Abhisar

Answer 2

@iambatman to the rescue?

Answer 3

is it just normal 4kw? i mean is there a formula if the bulbs r connected in series?

Answer 4

Step 1: Find the power.
Step 2: Find the energy.

Answer 5

Also, you can safely eliminate b and c because they're not even units of energy.

Answer 6

for each bulb it is 1kw....i m confused about the series thing

Answer 7

ohh..yes..:P

Answer 8

Oh ok, so do you know how the circuit looks like, you know the power formulas right?

Answer 9

Is it in general you don't know what a series circuit is?

Answer 10

yeah...lets suppose that...i hv forgot everything
i know d basic formulas...

Answer 11

\[P \propto V^2\]Now, when you connect four bulbs in series, then the voltage would get divided by 4 for each, and so the new power for each bulb would be the \(P/16\). Four bulbs would consume power \(P/16 \times 4 = P/4\). Here, \(P = 100 ~W\), so the power consumed by each is \(25 ~W\). Multiply that by 10 and you get \(E = 250 ~W\cdot h\).

Answer 12

in series the voltage gets divided equally...cool...and when in parallel?

Answer 13

In parallel circuits the components all have the same voltage

Answer 14

In paralel the voltage is same for each ..

Answer 15

What do you think? :)

Answer 16

and how does p become directly proportional to v2? is there some logic behind it?

Answer 17

\[P = V^2/R\]

Answer 18

yeah...

Answer 19

Here is a few things I guess you can remember for series and parallel circuits, each component in a series circuit has the same current,

Answer 20

ok so in series I remains constant. then y cant we use this formula...p=vi and as I is constant. p is directly proportional to v?

Answer 21

Warning...I AM DUMB IN PHYSICS..:P

Answer 22

Didn't mean to post that right away haha, went tab and it posted that but...\[R_{series} = R_1+R_2+R_3+...\]and if you know Kirchoff's Voltage Law it states "The sum of voltage changes going around complete circuit is zero"
So if you take delta V1+delta V2 +...etc = 0

Resistor: always has a voltage drop
Battery: V increases when +and decreases when -

Parallel:
all the components have the same voltage
\[\frac{ 1 }{ R_p } = \frac{ 1 }{ R_1 }+\frac{ 1 }{ R_2 }+\frac{ 1 }{ R_3 }+...\] and Kirchoff's current law here states I total = I1+I2+I3+...etc haha.