Watts/lightbulb physics question?

Question

which draws more current, a 100 W lightbulb or a 75 W bulb? which has higher resistance?

Please give explanation. Thank you!

Answer 1

lets see what i remember

W (watts) are a measure of WORK

1 W = 1V * 1A

A = ampere (amps), the measure of current

House plugs are 125 Volts (assuming you live in north america)

100W = 125x
75W = 125x
where x = number of amps

100/125 = x
75/125 = x
for the 100W bulb, it would draw 4/5 Amps
for the 75W bulb, it would draw 3/5 Amps

meaning the 75W bulb draws less current, explaining why it gives off less light


as for the resistance
according to Ohm's Law, Resistance = Voltage/Current

for the 75W
R = 125/(3/5)
R= 625/3
R= 208.333 Ohms

for the 100W
R = 125/(4/5)
R = 625/4
R = 156.25 Ohms

The 100W bulb has less resistance, and it draws more current.

Answer 2

A 100 W bulb pulls in more current than a 75 W bulb. A formula for power is P = V I, where P stands for power, V is voltage, and I is current. Voltage is the same in both cases. Consequently, P is directly proportional to I. The greater I is, the larger power becomes.

To answer your other question, you need Ohm's Law, in addition. This states that V = I R, where R denotes resistance. Solving for R, R = V / I; and since I = P / V,

R = V / P/V = V² / P

As before, V, and thus V², are constants. Therefore, R is inversely proportional to P; the larger P is, the smaller R gets.

As a matter of fact, current for a 100 W bulb is 0.8333 A; for a 75 W lamp, 0.625 A, assuming V = 120 V. Resistance of 100 W bulb: 144 Ω; resistance of 75 W bulb: 192 Ω.

Hope this has clarified this matter for you.

Answer 3

First let us get our terms clear. Energy in watts = Voltage in Volts multiplied by current in amperes.

So, if one bulb is consuming 100W and the other 75W, and since it is assumed that the voltage remains same, it is obvious that the 100 watt bulb is drawing more current than the 75 watt bulb. Since Voltage is the driving force, a higher resistance results in a lesser current and a lower resistance in a higher current. So, the 75 watt bulb has a higher resistance than the 100 watt bulb. Clear?

Answer 4

answer lies in two equations V= IR
and wattage = V I I is current V is voltage r - resistance
wattage higher means more power V voltage is always the same 230V at hom e or 110 V in america

so since W= VI current drawn in 100 W bulb is more
since R = V/I with v constant the bulb with larger current has lower resistance so R (resistance) in 100 W bulb is lesse

Answer 5

Watt is the unit of POWER not work because work is the change of energy which is measured in joule (J).
100W bulb draws more current and its resistance becomes greater.
This is shown in the formula, P=VI or P= (IR)I
Solving for resistance it is R=P/(I)(I)
Notice that resistance is directly proportional to power so it means that as resistance increases power increases too.

Therefore, 100W bulb has greater resistance to 75W bulb