how does resistance in water change with temperature?
351963
You are talking about viscosity of a liquid. In short: as temp goes up, viscosity or resistance goes down (however, this is not true for all liquids).\n\nViscosity is a measure of the resistance of a fluid to deformation under shear stress It is commonly perceived as "thickness", or resistance to pouring. Viscosity describes a fluid resistance to flow and may be thought of as a measure of fluid friction. Thus, methanol is "thin", having a low viscosity, while vegetable oil is "thick" having a high viscosity.\n\nBasically in a liquid you have a bunch of molecules smashing into each other at a certain "speed". The higher the temperature the faster they move around and the more "spread out" they become. Therefore as temperature goes up it becomes easier for things to move through the liquid and vise versa. Of course, this is true for most liquids but not all. See below for a great site that explains more.
361002
The convection of heat in the water carries warm water from the bottom of the water, nearest the warm earth, to the surface and back.\nThis motion maintains enough warmth throughout the water to prevent the fish from freezing.  The bodies of the fish also enables them to survive in near freezing temperatures by moving constantly.\nConvection always occurs, in Summer and Winter.  And the pattern never changes.
310551
The water level will neither go up nor down.\nSuppose we have an ice cube of mass m floating in the water. In equilibrium, it will have to displace enough water to support its weight. It is V=m/d\nNext when the ice has melted, it turns into water of volume: V= m/d! exactly the same volume as it displaced before. So the added volume is the same, so the level of the water will not change.
695376
The resistance of the filament of the lamp varies with temperature. When the filament is at room temperature the resistance is much lower than when it is white hot. \n\nCurrent = V/R. If the voltage is constant and the resistance increases, the current decreases.
106190
This seems like a homework problem...I'll give you a clue.\n\nsince, the ice is not changing temperature, all you need to do is figure out how much energy(per kilogram) it takes to ice into water...then multiply that number by 0.3.\n\nI'm guessing there will be a number in your book somewhere stateing the required energy to change 1 kilo of ice to water.
596165
Given a fixed power of heat input water would take longer due to its specific heat capacity being large.  4180Joules/kg/degree, compared with 450 for iron & 880 for Aluminium (figures STRICTLY only from memory and not to be relied on)\nOther than that are consideration of good conduction of heat in metals versus convection transporting the heat quickly within the water.\nAlso practically speaking, you might need to allow for evaporative heat loss from the water surface.
813595
a thermistor is a resistor whose resistance changes with temperature. Because of the known dependence of resistance on temperature, the resistor can be used as a temperature sensor.\n\nSo, add a thermistor into a simple circuit with a power supply and a meter to measure current and you have the essence of a device to measure temperature.\n\nGet a bucket, fill it with ice and leave it till the ice has half melted. The temperatue of the water will be 0 degrees C. Pop in the thermistor (suitably electrically insulated) and measure the current.\n\nBoil a pan of water on the stove. As it's bubbling the water will be exactly 100 Degrees C, and again measure the current.\n\nUsing both values you can calibrate your new electronic thermometer!
981166
I assume that you mean that the resistance of the solution kkeps rising with time. If you are using a Dc based system, then depending on the conductivity (1 over the resistance) electrolysis products may be building up at the electrodes and increasing the resistance. A yourself a good conductivity meter and this should eliminate the problem.\n\nThe resistance of a solution will dpend on the area of your electrodes, the distance bewteen them ,the concentration of dissolved salts in the water and the solution temperature. You will have a few things you will need to keep standard.
480166
If you have an equal volume of hot and cold water the cold water will be heavier.  This is because when you heat up a substance it become less dense, and in general when you cool down a substance it becomes more dense.\n\nThe exception to the rule is water though.  Water is most dense at 3 degrees cesius, after that it start to take a crystalin form and when it freezes actualy expands.  \n\nso long as you are not saying that the cold water is 1 degree and the hot water is 3, then the cold water will be heavier\n\n\nBut remeber it is not by much in any case
289316
They are often different due to the different water temperatures.  The total amount of dissolved salt in water decreases with temperature.
1117920
It will be water at 100 degrees that will stay that temperature longer b/c of the increased volume.  The only way to increase the temp is to increase the energy (temperature) while keeping the same mass (like putting flame under the container of water).  Since you are increasing mass AND energy, it balances out.
362368
Given:\nm <mass of substance> = 12.0g or 12/1000 kg\nc <specific heat capacity of water> = 4180J per kg per degree celsius\nt <change in temperature> = 20 degrees to 100 degrees i.e. 80 degree celsius\n\nFind:\nHeat req.\n\nSolution:\nHeat required or Q\nQ = m * c * t\n  = 12/1000 * 4180 * 80\n  = 12/10 * 418 * 8 (cancelling 0s of 4180&80)\n  = 12/5 * 209 * 8 (div. 418&10 by 2)\n  = 12/5 * 1672 (mult. 207&8)\n  = 20064/5 (mult. 12&1672)\n  = 4012.8\n\nAnswer = 4012.8 Joules or 4.0128 KJ
364536
Tungsten filament resistance changes with temperature but the change is stable and predictable. The rule of thumb for filament resistance as a function of temperature is R = R20*(1 + 0.0045*(T-20)), where R20 is resistance at 20C (room temp) and T is temperature in deg C (ref. 1). Operating temperature in lamps ranges from 2500C to 3000C (ref. 2). Thus at operating temperature, resistance will increase by a factor of 12 to 14 compared to the room-temperature value. In older electronic equipment, incandescent lamps were occasionally used as (sort of) constant-current sources.\nBecause the thermal time constant of a typical filament is a tenth of a second or more, 60 Hz AC will cause a ripple in the resistance (and the brightness), but this is stable. It might be possible to have large resistance oscillations if the resistance was proportional to a power of the temperature, and there could be a runaway condition (rapid burnout) if the resistance decreased with increasing temperature.
938890
The reason why the temperature does not change even though more heat is being added to the ice or water is that heat is needed to break the hydrogen bonds in ice to allow the phase change, and heat is needed to break the surface tension of the liquid to make water vapor.  Until all the bonds are broken there cannot be any increase in temperature.  Remember that temperature is just a macro measurement of the kinetic energy of the moving molecules.
771240
Almost any impurity in water will have the effect of raising the temperature at which it boils.
109177
i believe its because the boiling point of water is only 212 at normal atmospheric pressure, so if the pressure is changed the boiling point does too.
621304
If you are dealing with a reaction involving ammonium carbonate in solution, and are then measuring the temperature rise, you need the heat capacity of water, not ammonium carbonate!\n\nPlease post the whole problem if that is not enough to get you started.