milkman measured... (1 Viewer)

[SSR Remembered 4EVER]

Oil drops are inherently neutrally charged but by passing them through X rays he ionised them.
Hence there was an excess negative charge resulting in the oil drop to become negatively charged.
It's this negative charge that Millikan measured right? Like the excess negative charge.

 

[d1zzyohs]

nah;
he measured the charge of the electron. yes this charge was negative, but:
1. he didn't know what the fundamental charge of an electron was. so;
2. he did multiple tests at different masses and ionisations;
3. he then found the rate of change through these multiple results;
4. and as he knew that the charge would be a multiple of the fundamental charge -
he was able to figure out the elementary charge of an electron.

 

[Bob99]

nah;
he measured the charge of the electron. yes this charge was negative, but:
1. he didn't know what the fundamental charge of an electron was. so;
2. he did multiple tests at different masses and ionisations;
3. he then found the rate of change through these multiple results;
4. and as he knew that the charge would be a multiple of the fundamental charge -
he was able to figure out the elementary charge of an electron.

for your step 3, didn't he instead find the smallest difference in mass between different oil drops? And then he determined that the smallest difference will be the mass of an electron, and then did all the math/physics magic.

 

[Run hard@thehsc]

for your step 3, didn't he instead find the smallest difference in mass between different oil drops? And then he determined that the smallest difference will be the mass of an electron, and then did all the math/physics magic.

this is what I was taught as well

 

[Run hard@thehsc]

for your step 3, didn't he instead find the smallest difference in mass between different oil drops? And then he determined that the smallest difference will be the mass of an electron, and then did all the math/physics magic.

also how did he find the mass using terminal velocity

 

[SSR Remembered 4EVER]

also how did he find the mass using terminal velocity

It's term velocity so no net force I mean drag cancels out weight he then equated both and did the math to find out mas of the oil drop not the electron

 

[Run hard@thehsc]

It's term velocity so no net force I mean drag cancels out weight he then equated both and did the math to find out mas of the oil drop not the electron

can you show me how he used the term velocity pls - I know he equated the weight and electric field force together to get (mg = qE --> Q = mg/(v/d)), but how did he use the diameter and term velocity of the oil drops to get the mass of the oil drops themselves? Thanks!