ratio of charge to mass of electron J.J. Thompson (1897): deflect electron beam using field E- yE = estimate of electron if known q/m vx Using to balance B-field E-field (since ) calculate = 1.76 x 1011 C/g q/m measured charge of electron R.A.Milikan (1909-11): 1.charge oil drop by rubbing against nozzle of atomizer 2. experiences upward force due to applied qE E-field 3. balance against gravity terminal velocity of gravity fall (measure by timing drop) vg: terminal velocity of rise (depends on q: measure series of vE: vE) experiment with many different charges on drop set of values for , vE q all integer multiples of one value = 1.6 x 10-19 C qe mass of the electron
J.J. Thompson (1897): ratio of charge to mass of electron deflect electron beam using E- field yE = estimate q/m of electron if vx known Using B-field to balance E-field (since ) calculate q/m = 1.76 x 1011 C/g R.A.Milikan (1909-11): measured charge of electron 1.charge oil drop by rubbing against nozzle of atomizer 2. experiences upward force qE due to applied E-field 3. balance against gravity vg: terminal velocity of gravity fall (measure by timing drop) vE: terminal velocity of rise (depends on q: measure series of vE) experiment with many different charges on drop set of values for vE , q all integer multiples of one value qe = 1.6 x 10-19 C mass of the electron