chaturbhuj poddar


{ City } deoghar
< Country > india
* Profession * rerd un professor
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Name any two elementary particles which have almost infinite life time.

Shivam,

1 Nuclear Physics 9287

Cadmium rods are provided in a nuclear reactor.Why?

3 Nuclear Physics 7351




Answers / { chaturbhuj poddar }

Question { Eskom, 25053 }

if 100W and 200W bulbs are connected in series to a supply
which bulb will glow brighter and why


Answer

Let us suppose that the first bulbs is marked as 100W-200V and the second bulb as 200W-200V, and both are connected in series to 200V d.c. supply to make easy calculation.
Resistance of 100W bulb R1 = V^2/P = 200*200/100 = 400 ohm,
Resistance of 200W bulb R2 = V^2/200 = 200*200/200 =200 ohm
Thus, Resistance of the combination = =600 ohm. current through each bulb = V/600= 200/600 =1/3 A
Heat produced by 100W bulb per second H1=I^2*R1=(1/9)*200J/sec
Heat produced by 200W bulb per second H2=(1/9)*400 J/s.
H2 is greater than H1. Thus, 200W bulb will glow brighter.

Is This Answer Correct ?    14 Yes 38 No