## Sunday, September 12, 2010

### SPA Q4_N99

Aim: To investigate how the vol flow rate of a concentrated salt soln depends upon the magnetic field strength, keeping the concentration constant .
Diagram: Do not copy diagram again. Draw a circuit diagram with coil , battery, rheostat and ammeter.
Procedure:
1. Set up the circuit as above.
2. Set the variable resistor to a maximum and measure the magnetic field strength B between the coils using a Hall probe connected to a data logger and computer.
3. Open the tap at the end of the pipe and collect the soln at the start of the stopwatch.
4. Measure the vol of soln v, using a measuring cylinder and time taken, t from the stopwatch.
5. Calculate the vol flow rate V = v /t
6. Repeat steps 2 to 5 by varying the value of B to obtain 6 sets of v and t.
7. Plot a graph of lg B vs lgV assuming the equation is B = kVn . If the graph is linear then equation is valid, the grad = n and intercept = lg k.
8. To investigate the how the flow rate depends on concentration of soln , the B is kept constant.The concentration can be varied by adding more mass of salt into the same amount of water. C = m/vol.

Reliability :
The Hall probe is placed perpendicular to the coil.
The current through the sol is kept oonstant.
The expt is repeated and average value is calc .
Safety :
The current through the coils is large , hence do not touch with bare hands.
Place bricks on retort stand to prevent the apparatus from toppling.,