Exam paper question.
What you are refering to is the use of a variable resistor. It has a shaft on it that when turned either clockwise or counter clockwise it dims or brightens the bulb. It does this by proportinally dropping voltage accross itself. However, a better method would be to use a series resonance circuit using an inductor and capacitor. This would dissipate less electrical energy as heat. Unfortunately, I can't send you a jpeg of this here but do a google for resonance and what you need will be there.
Depending on the situation. The purpose of the rheostat is use to change the resistance of the circuit. The rheostat is use to define Ohm Laws the 2nd situation is use to find out what the fixed resistor's resistance. 3rd purpose : used to control the resistance of circuit. eg Radio
If the bulb is of the incandescent variety, then reducing the current in the circuit will do this.
If a rheostat is connected in parallel with a light bulb, the setting of the rheostat should have no effect on the performance of the light bulb, as long as the power supply is able to maintain its output voltage and deliver the current demanded by their parallel combination.
Then the brightness of the light buld increases.
A variable resistor can be connected in series with a light bulb in a circuit. By adjusting the resistance of the variable resistor, the current flowing through the circuit changes, affecting the brightness of the light bulb. Increasing the resistance decreases the current, resulting in lower brightness, while decreasing the resistance increases the current, leading to higher brightness.
Independent variable: the number of cells in the circuit. Dependent variable: the current measured by the ammeter. Control variable: resistance of the resistor, type of light bulb.
A: It is not a filter but rather a limiting resistor for the current.
If the resistance of the variable resistor increases, the current flowing through the circuit decreases. As a result, the bulb will emit less light or may not light up at all, depending on the magnitude of the resistance increase.
In some circumstances a filament bulb is used as a variable resistor. As the filament heats up, its resistance increases. This effect is used in some automatic gain control circuits; as the signal level increases, the changing resistance of the bulb can modify the feedback level in order to hold the level constant.
If your batteries were in series the total voltage would be 6 volts, and it the bulbs were in series you would need a resistor to keep them from burning out. In order to know how many ohms the resistor would need to be you would have to know the wattage of the bulbs, or the resistance of the bulbs. If you don't know the best thing to do is use a variable resistor. Then you can adjust it or the brightness that you want.
To effectively control the brightness of a LED bulb using a dimmer switch, make sure the dimmer switch is compatible with LED bulbs. Adjust the dimmer switch to increase or decrease the voltage supplied to the LED bulb, which will change its brightness. Experiment with different settings on the dimmer switch to find the desired level of brightness.
You alter the brightness of a bulb by changing the voltage or frequency that is applied to the bulb.
A pencil has nothing to do with the brightness of a light bulb.
Ordinarily you will have two variables in your experiment. These are the dependent variable, and the control variable.For example if you were measuring the fuel consumption in a car at various speeds, then you would vary the speed as your control variable, and measure the fuel consumption as the dependent variable.In this example, the speed is the easier one for you to vary.If I wished to determine the light bulb life at various voltages, it would make sense to control the voltage as your control variable, and measure the running time (or maybe the brightness) as a function of the voltage.
The relationship between voltage and brightness of a bulb is directly proportional. As voltage increases, the brightness of the bulb increases because higher voltage provides more energy for the bulb to emit light. Conversely, decreasing voltage reduces the brightness of the bulb.
lower the voltage by using a different power source or by placeing a variable resistor in series with the light bulb.