In a circuit the is fitted with a bulb, i m sorry is the factor that influence brightness of the bulb: present in the circuit or the voltage readily available by the battery in the circuit?



which is the aspect that affects brightness of that bulb, present in the circuit or the voltageBoth. It"s the strength that ultimately causes the filament to acquire hot and also emit visible black body radiation.

You are watching: What determines the brightness of a light bulb in a circuit

Power is voltage times current, for this reason both matter.

However, you have the right to only manage one level of freedom. The pear dictates the other. This solitary degree of freedom can be expressed various ways. Two of castle are addressing the current and fixing the voltage. Once you fix one of these, the resistance of the bulb implicitly fixes the other.

Note the the resistance that a pear varies substantially with temperature. The is much higher when the bulb is emitting irradiate than when it is sitting cold and unpowered. However, that still doesn"t let you fix both independently. That only method that the relationship between voltage and also current changes with the collection point.

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answered might 4 "17 in ~ 14:13

Olin LathropOlin Lathrop
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If you think of the light element, which might be a size of tungsten or the like, as a resolved resistor that R ohms, the current in the resistor is identified by:

$$ v = R~ i, $$

Ohm"s Law. The higher the voltage v the higher the current. If the brightness is led to by a circulation of electrons v the filament, a higher voltage will--all things being equal-- drive more electrons to circulation through the filament.

So the brightness is a role of both current and also voltage, and also can be claimed to depend on both. That is, we can write $v(i) = R~i$ or $i(v)=v/R.$

We can be tempted to say that the intensity ns of the light is proportional to current, $I \propto ns $ but we would need to remember the $i $ is a duty of $v$ and also put $I \propto i(v)=v/R.$

This can get arbitrarily complicated, since intensity the the light might not it is in proportional to present in a basic way, and also the precise behavior of electrons in a circuit counts on the exact conditions and the nature of the components. For example, together comments listed below note, the resistance may not be constant, yet may it is in a function of temperature.

An obtainable article on exactly how resistance might vary in a light bulb is offered here. A plot of i vs. V shows that the resistance R is not in basic constant. Come characterize the circuit in terms of V and I you could have to deal with $\fracdvdi=f(i)$ or take some measurements to gain a quantitative idea.