magnetism

Steering paramagnetic Leidenfrost drops in an inhomogeneous magnetic field

Student Manual

The Leidenfrost Effect is a phenomenon in which a liquid drop levitates on a surface that is significantly hotter than its boiling point. When we create Leidenfrost drops using a paramagnetic liquid, such as oxygen, we end up with liquid drops that hover above a surface with negligible friction, and since oxygen is paramagnetic, can be controlled by a magnetic field.

Software Code Tracker&nbsp(Download)
Experiment Code 2.23
Version August 28, 2018 Version 2018-1

Further Readings and References


Pictorial Procedure

Hardware Description

The copper cone is 10cm in height and 10cm in diameter. It holds enough liquid nitrogen to get a supply of liquid oxygen drops for around a couple of minutes. Underneath the tip of the cone is an aluminium bar with a depression along it’s axis. This is to make sure that the drop moves in a straight line as it enters the horizontal sheet. It allows us to vary the initial displacement of the drop (as explained in the video). This sheet is made of plexiglass, which is a cheap solution, but has some problems. The scratches on the surface of this sheet are very prominent in light, so we use a permanent marker to reduce light reflecting from the scratches. The screws near the corners of the sheet allow us to make sure that the sheet is horizontal. This is to ensure that the only force affecting the motion of the drops is the magnetic force. However, since this is a low cost setup and we only ensure that the sheet is horizontal using a spirit level, gravity does affect drops at very slow velocity. The plexiglass walls around the cone ensure that very little nitrogen vapours enter the recording area and makes sure the video recordings are clear and easy to analyse.

We need to make sure that we make no contact with any cold surface during the experiment. We use gloves for handling the glass that is used to pour liquid nitrogen. The cone must not be touched during the experiment, and even after the nitrogen has evaporated. The aluminium bar is not cold enough to be dangerous, but should still preferably not be touched with bare hands. The copper cone should be stable enough so that it can’t be accidentally tipped over while performing the experiment.

 

By Azeem Iqbal | Lab 2
DETAIL

Finding the Earth’s Magnetic Field by Twisting Magnets

Student Manual

The objective of this experiment is to use the oscillation of magnets in order to determine the earth’s magnetic field B. When we suspend magnets vertically pressing upon a wire, allow these to align in the north-south direction, and then slightly nudge these magnets, they will start oscillating in a horizontal plane. In fact, the magnets twist due to the torque exerted by the earths magnetic field.

Experiment Code 1.8A
Version 1 August 2018- 2018-v1

Further Readings and References


Pictorial Procedure

DETAIL

A dipole oscillating in the earth’s magnetic field

Magn_oscillatorThe group determined the earth’s Magnetic field B using a pair of magnets that oscillate about a vertically suspended wire. Magnets when suspended in space respond to the influence of the Earth’s magnetic field. Hence their oscillations are an accurate representation of the value of B. The experiment was performed using different wires and threads. The magnetic moment was determined from the space-dependent magnetic field variation and finally this was used to estimate B.

 

By Azeem Iqbal | Physics Studio
DETAIL

Faraday’s Effect

Student Manual

This experiment extends the concept of optical activity of chiral solution to magnetically induced birefringence through the historically important Faraday Effect, which reveals the rich interplay between optics and magnetism.

Sample Results Faraday rotation varies linearly with magnetic field
Maximum rotation is observed when analyzer is oriented at 45 degree w.r.t polarizer
Hardware Manual Equipment used in this experiment
Lock-in Amplifier
Experiment Code 2.6
Version 6 May 2014

Further Readings and References


Pictorial Procedure

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DETAIL

Observing Hall Effect in Semiconductors

Student Manual

This experiment introduces students to the Hall Effect which is a fundamental principle of magnetic field sensing. Students will measure Hall coefficient and carrier charge concentration in a given semiconductor crystal which will help them to understand important concepts in semiconductor physics. In this experiment students will also learn the relationship between current and magnetic field in an electromagnet as well as in a semiconductor material.

Sample Results Hall effect plots
Experiment Code 1.12
Version 21st September 2015, 2015-v2

Further Readings and References


Pictorial Procedure

1. Provided equipment for this experiment.

1. Provided equipment for this experiment.

2. Connection of electromagnet with power supply.

2. Connection of electromagnet with power supply.

3. Placement of the Hall probe in between the pole pieces of electromagnet.

3. Placement of the Hall probe in between the pole pieces of electromagnet.

4. Side view of printed circuit board (PCB) and Hall probe placed vertically in between the pole pieces of electromagnet.

4. Side view of printed circuit board (PCB) and Hall probe placed vertically in between the pole pieces of electromagnet.

5. Top view of printed circuit board (PCB) and Hall probe placed vertically in between the pole pieces of electromagnet.

5. Top view of printed circuit board (PCB) and Hall probe placed vertically in between the pole pieces of electromagnet.

DETAIL

Electromagnetic Induction and Working of Read-Write Operations in Magnetic Media

Student Manual

The experimental objective is to use a Hall sensor and to find the field and magnetization of a magnet. We will also gain practical knowledge of magnetic field transducers, hard disk operation and data storage, visually and analytically determining the relationship between induced EMF and magnetic flux, and indirectly measure the speed of a motor.

Software Code codes
Sample Results Hall probe
Solenoid
Distance vs magnetic field strength
Geometric function vs magnetic strength
Experiment Code 1.8
Version 31st August 2015, 2015-v1

Further Readings and References


Pictorial Procedure

1. Provided apparatus

1. Provided apparatus

2. A Hall probe connected to the digital multimeter

2. A Hall probe connected to the digital multimeter

3. Voltage value shown by the multimeter when Hall probe is connected to the computer

3. Voltage value shown by the multimeter when Hall probe is connected to the computer

4. Attaching a disk magnet to the steel meter rule

4. Attaching a disk magnet to the steel meter rule

 

5. Hall sensor's flat face is perpendicular to the magnetic axis of the disk magnet

5. Hall sensor’s flat face is perpendicular to the magnetic axis of the disk magnet

6. Voltage measurement using Hall probe

6. Voltage measurement using Hall probe

7. Measuring the diameter of a disk magnet using vernier calliper

7. Measuring the diameter of a disk magnet using vernier calliper

8. All the M-files must be in the current directory of MATLAB

8. All the M-files must be in the current directory of MATLAB

9. Labview file for observing induced EMF and magnetic flux

9. Labview file for observing induced EMF and magnetic flux

10. Mounting a solenoid

10. Mounting a solenoid

11. Setup for observing induced EMF and magnetic flux using a solenoid

11. Setup for observing induced EMF and magnetic flux using a solenoid

12. Mounting a Hall probe with flat face perpendicular to the magnetic axis

12. Mounting a Hall probe with flat face perpendicular to the magnetic axis

13. Setup for observing magnetic field using a Hall probe

13. Setup for observing magnetic field using a Hall probe

DETAIL

Magnetic Phase Transitions of a Ferromagnetic Alloy

Student Manual

This innovative experiment entails the determination of the Curie point of a ferromagnetic alloy. An alternating current is passed through the alloy, (also used as a heating element in industrial furnaces). The alloy, at room temperature, is attracted towards a strong permanent magnet while the voltage, current and time are constantly monitored. As the alloy heats up, a point reaches where the alloy loses its magnetism and snaps away from the magnet. The Curie temperature is then determined from the current, voltage, time, surface area, length of the alloy and its emissivity. This experiment will be performed in the close supervision of the instructor, who will guide the students through the appropriate safety protocols.

Hardware Manual Resistance Heating Alloys and Systems for Industrial Furnaces
Experiment Code 1.4
Version 31 October 2013

Further Readings and References


Pictorial Procedure

1. Provided apparatus

1. Provided apparatus

2. Connecting a digital volteter to the variac

2. Connecting a digital volteter to the variac

3. Clamping a clamp meter to any one of the variac output lead

3. Clamping a clamp meter to any one of the variac output lead

4. Set the variac at 0V, switch on the mains supply and press green START button

4. Set the variac at 0V, switch on the mains supply and press green START button

5. Checking for current leakage in the control box

5. Checking for current leakage in the control box

6. Current leakage check in the pole

6. Current leakage check in the pole

7. Current leakage test in the variac

7. Current leakage test in the variac

8. Testing the emergency stop button

8. Testing the emergency stop button

9. Circuit breaker check

9. Circuit breaker check

10. Set variac at 22V. The operating voltage range lies between 22-30V

10. Set variac at 22V. The operating voltage range lies between 22-30V

10. Set variac at 22V. The operating voltage range lies between 22-30V

11. Kanthal wire attached to the magnet

Curie_12n

12. Kanthal wire snapped away

DETAIL

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