Laboratory Methods

Question 1

Sample variance

Answer 1

Question 2

Simple propagation of error (for uncorrelated errors)

Answer 2

Question 3

General propagation of error

Answer 3

Question 4

Error on f = AB and f = A/B

Answer 4

Question 5

Error weighted average

Answer 5

Question 6

Error of the error weighted average

Answer 6

Question 7

Poisson distribution

Answer 7

Question 8

Error of the Poisson distribution for large N

Answer 8

Question 9

Time between Poisson events

Answer 9

The time between Poisson events follows an exponential distribution. Specifically, if one event falls at time t = 0, the time of the next event’s arrival is distributed as

Question 10

Complex impedance of a capacitor, inductor, and resistor

Answer 10

Question 11

High-pass filter

Answer 11

High frequencies pass, low frequencies attenuated

Question 12

Low-pass filter

Answer 12

Low frequencies pass, high frequencies attenuated

Question 13

Diode

Answer 13

Allows current to flow only in one direction, from anode to cathode in the picture below. No current can flow until a minimum bias voltage is applied - typically about 0.7 V for a silicon diode. Apart from this, the voltage drop is essentially indepenent of the current. Uses: turn AC into DC, reroute current away from sensitive components (if the voltage surges, the diode starts conducting, resulting in an almost short circuit at high enough voltages)

Question 14

Op-amp

Answer 14

(note that the op-amp has a maximum output voltage)

Question 15

AND gate

Answer 15

Question 16

OR gate

Answer 16

Question 17

Average path length of an alpha particle

Answer 17

Question 18

Average path of a high energy electron

Answer 18

Question 19

Radiation collision targets

Answer 19

• Nuclei interact almost exclusively with atomic electrons
• Electrons can either interact with atomic electrons or atomic nuclei (although the latter is still more rare)

Question 20

Minimum ionizing particle

Answer 20

At relativistic speeds, all particles lose roughly similar amounts of energy per unit distance (about 1 keV / cm in air). This value is the minimum energy loss, and therefore relativistic particles are referred to as “minimum ionizing particles”.

Question 21

Photoelectric effect

Answer 21

Question 22

Compton wavelength

Answer 22

Question 23

Radioactive decay

Answer 23

Question 24

Half-life to mean lifetime

Answer 24

Question 25

Mean lifetime with multiple decay modes

Answer 25

Question 26

Collisional gas lasers

Answer 26

Medium is gas or gaseous mixture. Transitions are due to collisions between atoms. In a He-Ne laser, there are a huge number of possible laser levels, but a specific wavelength can be selected by placing the laser in a resonant cavity.

Question 27

Molecular gas lasers

Answer 27

Medium is again a gas, and the transitions are between *vibrational* energy levels. CO₂ is commonly used, as it is cheap and gives a rich vibrational spectrum.