The typical cold resistance of a 100 W incandescent lamp is
about 9.5 ohms
. If that resistance stayed the same with 120 V applied, Ohm’s Law tells us that the bulb would draw about 12.5 amps and dissipate about 1,500 watts.
Do light bulbs have resistance?
The filament in an incandescent bulb does not have a constant resistance
. If you take a bulb and increase the voltage across it, the current increases too. An increase in current means the bulb gets hot—hot enough to glow. As the temperature increases, however, the resistance also increases.
Do light bulbs have high or low resistance?
Incandescent light bulbs have a small filament which when heated begins to glow and emit light. The reason the filament heats up is because it
has a high resistance
, which means that as electrons move through the filament, they lose a lot of energy.
Does lower resistance mean brighter bulb?
An incandescent bulb’s brightness depends on a whole lot on resistance. The higher the resistance to current in the wiring, circuitry, and bulb, the lower will be the current, lower the power, and lower the brightness. Conversely,
lower resistance means more brightness
.
Which light bulb has the higher resistance?
A
60-watt bulb
has a higher electrical resistance than a 100-watt bulb. Because power is inversely proportional to resistance, when the power is less, the resistance is high.
How would you determine the resistance of the bulb?
- To find the resistance of a component, you need to measure:
- The resistance is the ratio of potential difference to current. …
- For example, 3 A flows through a 240 V lamp. …
- resistance = 240 ÷ 3 = 80 Ω
- If you plot a graph of current against potential difference for a wire, you get a straight line.
How do you calculate the resistance of a light bulb?
Since it involves the relationship of power voltage, current, and resistance, using the formula I=P/V with P and V known to find the current, and then using the formula
R=P/I^2
to find the resistance will be the right steps to take.
Why is a light bulb with more resistance brighter?
If a bulb needs a big p.d. for a given current then it must have a high resistance. So in series high resistance bulbs are brighter
because they have a bigger p.d. across them
. In parallel circuits low resistance bulbs are brighter because they have a bigger current through them for the same p.d.
Why bulb with higher resistance is brighter?
If a bulb needs a big p.d. for a given current then it must have a high resistance. So in series high resistance bulbs are brighter
because they have a bigger p.d. across them
. In parallel circuits low resistance bulbs are brighter because they have a bigger current through them for the same p.d.
Do long bulbs have more resistance?
The round bulb and
the long bulb just happen to have a different resistance
; this obviously has nothing to do with the fact that the globe of one bulb is round and the other oblong. It is helpful if the two bulbs which you find have a visible difference between them (e.g., brass base vs. chrome base). 2.
Which has more resistance a 60W or 100W bulb?
A
60-watt bulb
has a higher electrical resistance than a 100-watt bulb. Because power is inversely proportional to resistance, when the power is less, the resistance is high.
Which has a larger resistance a 100W light bulb or a 60W light bulb?
Take the voltage to be 230V for both the bulbs. Therefore,
60 watt lightbulb
has larger resistance than a 100 watt lightbulb.
Which is having more resistance a 220V 100W bulb or a 220V 60W bulb?
Answer: The
220V
, 60W bulb has more resistance. R = 220*220/100 = 484ohm (approx.) So, Case 2 has more resistance.
What is the resistance of a 40 watt bulb?
Since power, P, equals iV, P/V = i, so at 120 V, a 40-watt bulb draws 1/3 A. (The units in iV are (C/s)(N-m/C), or J/s, which are watts.) For a given resistance, V = iR, so the bulb’s resistance (when it has 120 volts across it) is 120/(1/3), or
360 ohms
.
What is the resistance of a 60 watt light bulb operated at 120 volts?
The 120-Watt bulb has the lower resistance; and using Ohm’s law, one would expect it also has the higher current. In fact, the 120-Watt bulb would have a current of 1 Amp and a resistance of 120 Ω; the 60-Watt bulb would have a current of 0.5 Amp and a resistance of
240 Ω
.
How do I calculate resistance?
If you know the total current and the voltage across the whole circuit, you can find the total resistance using Ohm’s Law:
R = V / I
. For example, a parallel circuit has a voltage of 9 volts and total current of 3 amps. The total resistance R
T
= 9 volts / 3 amps = 3 Ω.
