Part One: Electrons stick to Scotch Magic Tape and today you will estimate the number of...

 

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Part One: Electrons stick to Scotch Magic Tape and today you will estimate the number of electrons stuck to the surface of a piece of tape. Here are a few suggestions to get you started, but you will need to make some approximations to obtain an answer. You can place an excess negative electric charge on a piece of Scotch Tape as follows: Take a 20 cm length of tape and fold over a short section at one end to make a little handle. Put the tape, sticky side down on the lab bench and rub it to make good contact. Do the same with a second, identical piece of tape. Then quickly pull the strips up and bring the non-sticky sides of the tape near each other. PHYSICS 280 LABORATORY LAB01: COULOMB'S LAW (a) What happens? (Include drawing) Measurements: Need angle 0 and L, the length of the tape. O should be defined in your drawing. Put the measurements here that you need to estimate the charge, Q, on each of the pieces of tape. (Assume each piece has the same charge.) Analysis: (a) Estimate the number of excess electrons on the surface of one of the 20cm long pieces of tape, pulled from the lab bench. This should be an order of magnitude estimate and you are not expected to get an exact answerthere is none. You should be able to give a reasonable estimate. Note that a piece of half-inch-wide (1.2 cm) tape, which is 20 cm long, has a mass of about 0.262g. Must include diagram and x and y components of F=ma to find the equation Q. (b) What would happen if both pieces of tape did not have the same charge Q, but one had Q and the other Q2? Let Q = q8, and Q = 9+8. Now put Q1 and Q2 into F = K determine if F increases or decreases in magnitude. - |222| and r (c) Estimate the fraction of the surface molecules that now have an excess electron. HINT: How big is a molecule? Assume atom has volume (1 angstrom). Area of tape = L*W. NATOMS Area/(1 Angstrom) = Note 1 Angstrom = 10-10 m. fraction with excess charge = Number of excess electrons = (q from above)/NATOMS Part One: Electrons stick to Scotch Magic Tape and today you will estimate the number of electrons stuck to the surface of a piece of tape. Here are a few suggestions to get you started, but you will need to make some approximations to obtain an answer. You can place an excess negative electric charge on a piece of Scotch Tape as follows: Take a 20 cm length of tape and fold over a short section at one end to make a little handle. Put the tape, sticky side down on the lab bench and rub it to make good contact. Do the same with a second, identical piece of tape. Then quickly pull the strips up and bring the non-sticky sides of the tape near each other. PHYSICS 280 LABORATORY LAB01: COULOMB'S LAW (a) What happens? (Include drawing) Measurements: Need angle 0 and L, the length of the tape. O should be defined in your drawing. Put the measurements here that you need to estimate the charge, Q, on each of the pieces of tape. (Assume each piece has the same charge.) Analysis: (a) Estimate the number of excess electrons on the surface of one of the 20cm long pieces of tape, pulled from the lab bench. This should be an order of magnitude estimate and you are not expected to get an exact answerthere is none. You should be able to give a reasonable estimate. Note that a piece of half-inch-wide (1.2 cm) tape, which is 20 cm long, has a mass of about 0.262g. Must include diagram and x and y components of F=ma to find the equation Q. (b) What would happen if both pieces of tape did not have the same charge Q, but one had Q and the other Q2? Let Q = q8, and Q = 9+8. Now put Q1 and Q2 into F = K determine if F increases or decreases in magnitude. - |222| and r (c) Estimate the fraction of the surface molecules that now have an excess electron. HINT: How big is a molecule? Assume atom has volume (1 angstrom). Area of tape = L*W. NATOMS Area/(1 Angstrom) = Note 1 Angstrom = 10-10 m. fraction with excess charge = Number of excess electrons = (q from above)/NATOMS