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Why is a graph of voltage against current for a filament bulb curved?
Wiki User
∙ 9y ago
Because as current increases, heat increases and therefore resistance increases. Since resistance is the gradient of the graph, the gradient will increase and therefore the graph will curve. (The filament in the bulb is an non-ohmic conductor; its resistance is only constant at a constant temperature.)
Another Answer
Incandescent lamp filaments are manufactured from tungsten. Tungsten is classified as 'non-ohmic' or 'non-linear', which means that (in common with most materials, in fact) it does not obey Ohm's Law. For a material to obey Ohm's Law, the ratio of voltage to current (i.e. its resistance) must remain constant for variations in voltage -as you have discovered, tungsten doesn't do this, producing a curve, rather than a linear, graph. As the original answer indicates, the temperature coefficient of resistance of tungsten in such that, as it gets warmer, its resistance increases.
Those few materials that do obey Ohm's Law are called 'ohmic' or 'linear' materials.
Wiki User
∙ 9y ago
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Why is there a curve and not a straight line in the graph for a filament lamp?
I had to answer this and found out that............ The line on the graph that represents the filament lamp is curved because the resistance of it increases with supplied voltage Hope this is alright for you :) x
Why a bulb cannot be used to verify ohm's law?
A filament lamp does not obey Ohm's Law because, for tungsten, the ratio of voltage to current isn't a constant for changes in voltage. Metals such as tungsten are, therefore, termed 'non-linear' or 'non-ohmic'.There seems to be a major misconception surrounding Ohm's Law. Ohm's Law simply states that 'the current flowing along a wire, at constant temperature, is directly proportional to the potential difference across its ends'. For Ohm's Law to apply, the current/voltage graph line resulting from varying the voltage MUST be a straight line. If it is curved, then Ohm's Law doesn't apply. In fact, most metals and electronic components, such as diodes, do not follow Ohm's Law.So Ohm's Law is NOT a universal law and applies in very few circumstances.The equation R = V/I applies whether Ohm's Law is followed or not, because the ratio of V/I will always indicate what the resistance happens to be for that particular ratio. But the fact that you can use this equation under any circumstance doesn't mean Ohm's Law is applicable.
Why is Ohms law important in the electrical field?
Ohms law "V= RI" is the " F=ma or Newton's Law" of Electricity. It gives the quantitative relationship between the three important concepts of electricity, V=Voltage, I= Current and R= Resistance.AnswerOhm's Law is not really important at all, as it is not universal and applies to very few conductors and, then, only under very strict conditions. For a circuit to obey Ohm's Law, its ratio of voltage to current must remain constant for variations in voltage, and this is rarely the case! Most conductors, and most electric devices such as diodes, etc., simply do not obey Ohm's Law. In fact, some engineers and scientists would argue that Ohm's 'Law' should not be a law at all as it applies in so few circumstances.The problem is that many people, including many electricians, mistakenly think that Ohm's Law is represented by an equation that tells us the resistance is voltage divided by current whereas, in fact, this equation is derived from the definition of the ohm, and NOT from Ohm's Law.
What do you call a curved path followed by a projectile?
The curved path is called a trajectory
What causes the path of a projectile to be curved?
The gravitation forces are what causes the path of a projectile to be curved.
Why is the graph of the non-ohmic conductor is curved in nature?
Ohmic (or 'linear') materials obey Ohm's Law. That is, their ratio of voltage to current remains constant for variations in voltage. Ohmic materials, therefore, produce a straight line graph when we plot current against variations in voltage;Non-ohmic (or 'non-linear') materials do not obey Ohm's Law. That is, their ratio of voltage to current variesfor variations in voltage. This means that non-ohmic materials produce a curved line graph when we plot current against variations in voltage.
Why does the filament lamp does not follow Ohms Law give any example?
A filament's resistance value varies with temperature. When directly measuring resistance, the filament is off, and at or near room temperature. When the circuit is turned on to measure voltage and current, the filament's temperature will increase and the resistance value will increase. This makes it appear as though Ohm's law is wrong.AnswerThere is no difficulty; your experiment will simply prove that the filament of the lamp doesn't obey Ohm's Law.When you plot the results of current against voltage for a lamp's filament, obtained from your experiment, the result will be a curved line, indicating that the current is notproportional to voltage (due to a changing resistance). This shows that the filament doesn't obey Ohm's Law. To obey Ohm's Law, the result must be a straight-line graph.Although the resistance of the lamp can be found at any point along the curve from the ratio of voltage to current (i.e. R = V/I) at that particular point, the lamp does not obey Ohm's Law. Ohm's Law only applies when the ratio of voltage to current remains constant throughout the experiment.So no difficulty has arisen with your experiment, you have simply proved that Ohm's Law doesn't apply to the lamp filament. Believe your results!!
Why is there a curve and not a straight line in the graph for a filament lamp?
I had to answer this and found out that............ The line on the graph that represents the filament lamp is curved because the resistance of it increases with supplied voltage Hope this is alright for you :) x
Is ohms law applicable to filament?
Absolutely not! A tungsten filament is an example of a non-linear or non-ohmic material, and it does not obey Ohm's Law. Ohm's Law is a law of constant proportionality; in other words, for it to apply, the ratio of voltage to current must be constant over a wide range of voltages. Increasing the voltage of a tungsten filament to its rated voltage causes its resistance to increase around 15 - 18 times, compared with its 'cold' resistance. Therefore, the ratio of voltage to current changes significantly as the applied voltage changes -so it does not obey Ohm's Law.However, the ratio of voltage to current will always tell you what the resistance happens to be for any particular ratio. Since, for tungsten, because the ratio increases as the voltage increase, the resistance changes too.To summarise, for Ohm's Law to apply, there MUST be a linear relationship between voltage and current; with tungsten, the relationship is a curved line and, so, it is non-linear and does not obey Ohm's Law.
Is a light bulb an ohmic conductor?
For a material to be 'ohmic' or 'linear', it must obey Ohm's Law. For Ohm's Law to apply, the ratio of voltage to resistance must be constant for variations in voltage. An incandescent lamp's filament is manufactured from tungsten, which is 'non-ohmic' or 'non-linear' because the ratio of voltage to current changes for variations in voltage. In fact, MOST conductors and electrical devices (such as diodes) are non-ohmic. If you were to conduct an experiment that allowed you to record the variation if current flowing through a tungsten filament for variations in voltage, the result would be a curved graph line -in other words, a 'non-linear' (therefore, 'non-ohmic'), graph line. So, to directly answer your question, NO, a tungsten filament is not an ohmic material.
Why a bulb cannot be used to verify ohm's law?
A filament lamp does not obey Ohm's Law because, for tungsten, the ratio of voltage to current isn't a constant for changes in voltage. Metals such as tungsten are, therefore, termed 'non-linear' or 'non-ohmic'.There seems to be a major misconception surrounding Ohm's Law. Ohm's Law simply states that 'the current flowing along a wire, at constant temperature, is directly proportional to the potential difference across its ends'. For Ohm's Law to apply, the current/voltage graph line resulting from varying the voltage MUST be a straight line. If it is curved, then Ohm's Law doesn't apply. In fact, most metals and electronic components, such as diodes, do not follow Ohm's Law.So Ohm's Law is NOT a universal law and applies in very few circumstances.The equation R = V/I applies whether Ohm's Law is followed or not, because the ratio of V/I will always indicate what the resistance happens to be for that particular ratio. But the fact that you can use this equation under any circumstance doesn't mean Ohm's Law is applicable.
Why is an incandescent lamp nonlinear?
Because the more you heat up a conductor the more it's electrically resistant. So, when you increase the supply voltage across such a lamp, the current increases as well, but it heats up the filament, which in turn lowers the current. So, its current depends on 2 variables: voltage and filament temperature. That's why you find a discrepancy between the resistance you measure with an ohmmeter and the one you calculate by using its rated power.
Is there any similarity between the graphs plotted between voltage and current?
When you plot a graph of voltage against current, you can end up with a straight line or a curved line.If you have a straight line, then it shows that the change in current is directly proportional to the change in voltage and, so, the circuit is obeying Ohm's Law. If the graph is a curve, then the change in current is not proportional to the change in voltage and, so, the circuit is not obeying Ohm's Law.In the case of a straight-line graph, the gradient of the graph indicates the resistance of the circuit. The greater the gradient, the higher the circuit resistance.In the case of a curved-line graph, the gradient (i.e. the tangent) at each point along that curve will indicate the (changing) resistance at each of those points.
What obeys ohms law nichrome thermistor or diode?
Ohm's Law only applies when the ratio of voltage to current is constant for variations in voltage. If you were to plot a graph of current against voltage, and the result is a straight line, then Ohm's Law applies; if the result is a curved line, then Ohm's Law does NOT apply.Ohm's Law is NOT a universal law; in fact, if barely qualifies as a 'law' at all because, in most cases, it does not work!Nichrome alloy is designed to retain a constant resistance over a wide range of temperatures. So it is considered to be 'ohmic' or 'linear' because, when plotting current against voltage, it produces a straight-line graph, for variations in voltage. So, nichrome obeys Ohm's Law.Thermistors and diodes produce curved graph lines and, so, are considered to be 'non-linear' or 'non-ohmic', and do NOT obey Ohm's Law.
Do all electrical and electronic circuits obeys ohms law?
Ohm's law is always true. That's what makes it a law. What trips people up is that resistance is not constant. The law states that voltage is current times resistance. That is true, no matter what. The calculations can become complex, because resistance is not constant.Another AnswerProbably not. But it really depends on the shape of the characteristic curve for its application (e.g. diode). Despite being fundamental, Ohm's Law is one of the least understood so-called 'laws' in electrical engineering. It applies in so few cases, in fact, that many engineers and physicists argue that it should not be called a 'law' at all!Ohm's Law is not a universal law, and onlyapplies when the ratio of voltage to current is constant for variations in voltage. This only applies to linear or 'ohmic' devices. Most electronic devices are non-linear or 'non-ohmic' and these include vacuum tubes and solid-state devices, etc. Even some pure metals, such as tungsten, are non-linear -so incandescent lamps, for example, do not obey Ohm's Law.Ohm's Law only applies to conductors and circuit devices that produce a straight-line graph when current is plotted against variations in voltage. If the resulting graph is curved, then Ohm's Law doesn't apply. Period!Think about it: if you, say, double the voltage for a curved graph line, the resulting current doesn't double in value -so it can't be obeying Ohm's Law (which states that 'current is proportional to voltage').Of course, some vacuum tubes and solid-state devices have voltage/current characteristic curves that are partly-curved and partly-straight -in these cases Ohm's Law applies only the the straight-line parts of those characteristic curves, but not to the curved parts. Some devices have 'negative' curves, in which current increases when the applied voltage decreases -clearly these do not obey Ohm's Law, either!Having said that, for non-linear devices, you can use the ratio of voltage to current (= resistance) to find out what the resistance happens to be for any particular ratio of voltage to current -i.e. at a specific point along their graph line.
What is the nature of the current voltage graph for an unknown resistor?
Fixed-value resistors are normally manufactured so that they obey Ohm's Law -that is, the ratio of their voltage to current remains constant for variations in voltage, within specified limits. In other words, their resistance value remains constant for variations in voltage. This would produce a straight-line curve when plotted. Devices and materials that do not obey Ohm's Law (e.g. semiconductors, etc.) would produce a curved line.
Will semiconductors obeys the ohms law?
Yes and no. At any instant they follow ohm's la. However as they are nonlinear, as signals change they deviate from the standard ohm's law that passive components follow at all times.Another AnswerFor Ohm's Law to apply, the ratio of a conductor's (or device's) voltage to resistance MUST be constant for variations in voltage. In other words, if you plotted current against voltage, for variations in voltage, then the result MUST be a straight line. Ohm's Law does not apply at a particular instant.Hardly any material or device obeys Ohm's Law, because most produce curved lines. Transistors do not obey Ohm's Law and is described as being 'non-linear' or 'non-ohmic'.The equation, R = V/I, widely regarded as being 'Ohm's Law' is derived, NOT from Ohm's Law, but from the definition of the ohm.There seems hardly any credible reason to continue teaching 'Ohm's Law' as a 'law', as it applies to so few materials.
