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Does the resistance go higher or lower when a thermistor gets hot?
Wiki User
∙ 13y ago
the therminster will get hotter when the resistance is lowed
Wiki User
∙ 13y ago
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What is the current when a 60W lampis connected to 120v?
Since power is volts time amps, the current in a 60W lamp connected to 120V is 0.5A. Since a lamp is a resistive load, there is no need to consider power factor and phase angle, so that simplifies the explanation. ======================== Assuming this is an incandescent or halogen lamp (using a filament to make the light) there is a trick here: the resistance of a lamp filament varies with temperature and does not follow Ohm's law. The resistance will be much lower, thus the current will be much higher when the filament is cold, when the lamp is first connected. As the filament heats up, the resistance increases until it gets to a steady operating point of 0.5A. For a halogen lamp, the operating temperature is about 2800-3400K, so the R at room temperature is about 16 times lower than when hot... so when connected, the current is about 8A but drops rapidly. The current could be even higher if the lamp is in a cold environment. Non-halogen lamps operate at a lower temperature and would have a lower initial current--about 5A. And this all assumes the lamp is rated for 120V. If it is a 12V/60W lamp, the filament will probably break and create an arc, which may draw a very large current.
Why does power decrease when resistance increases?
First, this statement stands as long as voltage is constant. If you held the current constant then power would increase as resistance increases.V=IR. For a fixed voltage if you increase the resistance (R) then the current (I) will decrease - following the formula.Power = VI so as the resistance increases the value of VI (power) decreases as V is constant and I gets smaller.Therefore the power is decreasing as the resistance increases (when voltage is held constant).Hope this helps.
What happen when ammeter connected in parallel?
an ideal ammeter has zero or negligible resistance when this is connected in series no effective resistance would be added in the circuit so that the value of curret that we get is exactly of the circuit only. but when the ammeter is connected in parllel as it has zero resistance , the resistor to which it is connected in parllel gets shorted and due to his the effective resistance of the circuit is changed and so the effective current ... due to this the w=value measured by the ammeter would be different (incresed due to dec. in effective resistance)
If temperature increases than the resistance increase or decreases?
If temperature increases the resistance will also increase. This is why a light bulb is a non ohmic conductor. As the light bulb filament gets hotter its resistance will increase.Additional CommentsIt depends upon the material involved. In general, for pure metal conductors an increase in temperature will cause their resistance to increase. For insulators, an increase in temperature will cause their resistance to decrease -which is why excessive temperature is often the main reason why insulation fails. Alloys can be manufactured that will maintain a relatively constant resistance over a wide range of temperatures.Temperature affects resistance indirectly. What is actually being affected is the material's resistivity. Resistivity is one of the factors that determines resistance.The resistance of any given material can be calculated over wide range of temperatures, using the temperature coefficient of resistance for that material.
What is the principle of operation of LDR?
Working of light dependent resistor This circuit explains the principle of operation of LDR (light dependence resistor). The circuit has various applications like shadow alarm, automatic night/morning lamp. LDR, an acronym for light dependent resistor is a resistor whose resistance is dependent on light. The resistance of LDR is of the order of Mega Ohms in the absence of light and reduces to a few ohms in presence of light. In this circuit when the light falls on LDR, the resistance of LDR becomes low and the entire voltage drop takes place across the variable resistance VR1 (10K). As a result the base of transistor (T1) gets high input and it gets biased thereby glowing the LED. When no light falls on LDR, the resistance of LDR becomes high so almost entire voltage drop takes place across it and the base of transistor is at low potential. So transistor does not gets biased nor it becomes conducting, hence switching off the LED. The sensitivity of the circuit can be adjusted by varying the preset VR1. LDR, an acronym for light dependent resistor is a resistor whose resistance is dependent on light. The resistance of LDR is of the order of Mega Ohms in the absence of light and reduces to a few ohms in presence of light. In this circuit when the light falls on LDR, the resistance of LDR becomes low and the entire voltage drop takes place across the variable resistance VR1 (10K). As a result the base of transistor (T1) gets high input and it gets biased thereby glowing the LED. When no light falls on LDR, the resistance of LDR becomes high so almost entire voltage drop takes place across it and the base of transistor is at low potential. So transistor does not gets biased nor it becomes conducting, hence switching off the LED. The sensitivity of the circuit can be adjusted by varying the preset VR1.
Why does the resistance of a thermistor decrease as the temperature rises?
Some materials have negative temperature coefficients of resistance, and some have positive temperature coefficients. Carbon is an example of a substance with a negative thermal coefficient of resistance, so it's resistance will decrease as it gets hotter.
Does a woman's voice get higher or lower as she gets older?
A women's Voice gets lower. Just not as low as a man's voice.
Why do recipes change at higher altitudes?
The air pressure gets lower!
Why does a ball gets lower and lower when it bounces?
Some energy is dissipated (wasted) in every cycle - both during the rebound, and through air resistance.
Why does it get colder the higher you go to the mountain?
It gets colder the higher you climb a mountain because of the lower air pressure.
How does tempreture affect resistance?
Temperature has a positive relation on resistance. This is because as the temperature gets higher, the molecules in the surface move more, which will cause more resistance since the molecules will be moving and bumping into things.
When an atom gets charge?
When the number of electrons is higher or lower than the number of protons.
Why Boeing Airbus flies high?
Air drag / wind resistance gets lower as the air gets thinner. So planes save fuel by flying high.
What is an outliers effect on the mean?
if the oulier is REALLY high, the mean gets higher if the outlier is REALLY low, the mean gets lower
How do thermistors work in clothes dryers?
If the heat gets excessive the thermistor button will pop and switch the power off.
Why does the top part of the mountain still has snow on it but lower parts don't?
the higher you get the colder it gets
Why would a rising mass have low pressure?
It would because the higher it goes the lower it gets
