Year 2 E3

Question 1

The heart of an oscilloscope is

Answer 1

a special vacuum tube called the cathode-ray tube (CRT)

Question 2

CRT consists of four main parts

Answer 2

electron gun
vertical-deflection plates
horizontal-deflection plates
fluorescent screen

Question 3

Screen of the CRT

Answer 3

is coated on the inside with phosphor

which has the property of phosphorescence.

Question 4

what is the grid system on the fluorescent screen called

Answer 4

graticule

Question 5

Horizontal axis

Answer 5

is the line along which the time of the wave is measured

Question 6

Vertical axis

Answer 6

magnitude or amplitude of the voltage is measured

Question 7

Define Sweep

Answer 7

horizontal movement of the electron beam

Question 8

Define Sweep time

Answer 8

is the time taken for the trace to travel across 1 cm of the screen

Question 9

Define level

Answer 9

point on the input signal wave where the trace starts.

Question 10

Define channel

Answer 10

is the input terminal of the incoming vertical signal

Question 11

Define Probes

Answer 11

are used to make the electrical connection from the scope to the circuit under test
two types of probe are used: time 1 and times 10

Question 12

Define Astigmatism

Answer 12

to adjust the roundness of the beam spot

Question 13

Define amplitude

Answer 13

volts/div allows a distance of 1 cm vertically to represent an input from 10mV to 50V

Question 14

DC/AC ground coupling switch

Answer 14

DC direct coupling
AC alternate coupling
GND ground

Question 15

Chop/alternate control

Answer 15

ADD sum of ch 1 and ch2
ALT displays each channel alternately
CHOP switches between ch1 and ch2

Question 16

Sweep speed

Answer 16

time/div or sec/div: determine the rate at which the beam sweeps across the screen

Question 17

Oscilloscope calibration

Answer 17

Uses the PROBE ADJUST terminal

sends a square-wave voltage of 50mV peak to peak and Hz of 1 kHz

Question 18

Probe calibration

Answer 18

X10 probes has a voltage-dividing circuit in its body. Sometime need adjustment this is referred to as probe compensation

Question 19

Probe multipliers

Answer 19

x1 probe impedance of 1 Megohm

x10 probe impedance of 10 Megohs this decreases the value of input voltage by 1/10

Question 20

Shorts due to probe connection

Answer 20

if the ground side is unknown, do not connect the ground clip of the probe.

Question 21

Use of isolation transformer

Answer 21

reduces the change of short

must use ground lead

Question 22

Using two probes

Answer 22

when using two probes for simultaneous voltage measurements use only one ground clip