This experiment measures e/m, the charge to mass ratio of the electron. In the present experiment a beam of electrons is accelerated through a known potential, so the velocity of the electrons is known. A solenoid produces a uniform and measurable magnetic field at right angles to the electron beam. This magnetic field deflects the electron beam in a circular path. By measuring the accelerating potential, the current to the solenoid, , and the radius of the circular path of the electron beam, the ratio e/m is calculated.
The e/m apparatus by helical method consists of four major parts :
- Standard Solenoid of multi-turned layers fitted on wooden base.
- Power supply for Solenoid :
- I.C Regulated variable Power supply : 0 to 30 V @10 Amp.
- With Digital Voltmeter and Ammeter.
- Cathode Ray Tube Power supply :
- High Voltage 0 to 1000 V @100 mA.
- With Digital Voltmeter.
- Cathode Ray Tube mounted to movable inner side of the standard solenoid.
- Connecting jack.