What happens when you cover an LDR?
The preset resistor can be turned up or down to increase or decrease resistance, in this way it can make the circuit more or less sensitive. That means light must shine into the LDR for the circuit to be activated. Draw a circuit composed of the same components that activates when it is DARK (when the LDR is covered).
Why does voltage decrease with decreased LDR?
The light energy produces more free electrons which increases the current for a certain voltage across the LDR which means a drop in resistance.
How does a light Dependant resistor work?
LDRs (light-dependent resistors) are used to detect light levels, for example, in automatic security lights. Their resistance decreases as the light intensity increases: in the dark and at low light levels, the resistance of an LDR is high and little current can flow through it.
What happens when LDR resistance increases?
If an LDR is connected in series with a fixed resistor (i.e. the circuit is a potential divider) and the resistance of the LDR increases then its share of p.d. will increase. That is, p.d. across the LDR increases and p.d. across the fixed resistor will decrease.
What happens to LED when LDR is exposed to light?
When an LDR is exposed to a light of high intensity, the resistance value will decrease. It could drop from 1 MΩ to 2 kΩ. Circuit of a day/night switchnpn transistor is the control device, and an LED is the output device.
Does higher resistance mean higher voltage?
The current is directly proportional to the voltage and inversely proportional to the resistance. This means that increasing the voltage will cause the current to increase, while increasing the resistance will cause the current to decrease.
Does a thicker wire have more resistance?
The moving electrons can collide with the ions in the metal. This makes it more difficult for the current to flow, and causes resistance. The resistance of a thin wire is greater than the resistance of a thick wire because a thin wire has fewer electrons to carry the current.
What are the factors that affect electrical resistance?
There are several factors that affect the resistance of a conductor;
- material, eg copper, has lower resistance than steel.
- length – longer wires have greater resistance.
- thickness – smaller diameter wires have greater resistance.
- temperature – heating a wire increases its resistance.
Why resistance decreases with increase in area?
Adding more wires in parallel decreases the resistance of that circuit path. So, bigger cross sectional area = more wires in parallel = lower resistance. And hence the inverse proportionality relation is responsible for increase in area, decrease in resistance property.
How does changing the length of wire affect the resistance?
First, the total length of the wires will affect the amount of resistance. The longer the wire, the more resistance that there will be. More collisions mean more resistance. Second, the cross-sectional area of the wires will affect the amount of resistance.
What does not affect a material’s resistance?
Length and area affect resistance as well as type of material expressed with . Temperature does not affect resistance.
Does diameter affect resistance?
As the diameter of the wire increases, the resistance decreases. In fact, if we double the cross-sectional area then the resistance halves. This means that resistance is inversely proportional to the area of the wire.
What happens to the resistance if diameter of wire becomes half?
Resistance is inversely proportional to cross sectional area. So if the diameter is halved the cross-sectional area is quartered and the resistance is quadrupled.
What will happen to the resistance if the diameter is doubled?
When diameter is doubled, the resistance becomes R′=π(2d/2)2ρL=R/4.
What happens to area when length is doubled?
Assuming constant total volume, if you double the length, the area has to reduce by a factor of two. The total resistance increases by 2x due to the length increase, and increases by a factor of two due to the area reduction.
What happens to the resistance of conductor if its length is increased three times and diameter is halved?
Options: Resistance remains the same. Resistance is increased 3 times.