(a) The drum of a photocopying machine has a length of 42 cm and a diameter of 12 cm. The electric field just above the surface of the charged drum has a magnitude E of 3.0 × 105 N/C. What is the total charge on the drum? (b) The manufacturer wishes to produce a desktop version of the machine. This requires reducing the drum length to 22 cm and the diameter to 6.2 cm. The electric field at the drum surface must not change. What must be the charge on this new drum?

Step-by-step explanation:

The drum is in the form of charged cylinder .

Electric field near a charged cylinder = λ /2πε₀r

λ is linear charge density ,

3 x 10⁵ = λ /(2 x 3.14 x 8.85 x 10⁻¹² x 0.06)

λ = 2 x 3.14 x 8.85 x 10⁻¹² x 0.06  x 3 x 10⁵

= 10 x 10⁻⁷ C/m

Total charge on the cylinder

= .42 x 10 x 10⁻⁷

= 4.2 x  10⁻⁷ C

b )

New diameter = 6.2 cm

radius = .031 m , for same electric field

3 x 10⁵ = λ /(2 x 3.14 x .031 x 8.85 x 10⁻¹² )

λ = 2 x 3.14 x .031 x 8.85 x 10⁻¹² x 3 x 10⁵

= 5.168 x 10⁻⁷

Charge on the cylinder

=  5.168 x 10⁻⁷ x .22

= 1.25 x 10⁻⁷ C

Charge on new drum

= 1.25 x 10⁻⁷ C

see below

step-by-step explanation:

7.   there are 10 data points in the set.   the middle point is between 5 and 6.   the middle point in the top half is 8   and the middle point in the bottom half is 3. to find the iqr , take point 8 and subtract point 3

mid term   point 8 = 100   point 3 = 88

iqr = 100-88 = 12

final   point 8 = 93   point 3 = 78

iqr = 93 - 78 = 15

the final has the greatest iqr

6.   b - there is a high data value that causes the data set to be asymmetrical for the males: the data for males are high and asymmetrical .   there is an outlier for the males that skews the data

5.   the   iqr is a better measure of spread for the movies and basketball games.   since the basketball game has an outlier, we do not want to use standard deviation for measurement.  

3.   the exam median is much higher than the class median.   the median line is farther to the right on the exams

2.   there is no way to tell what the means are from the box and whisker plots.  

stew reads at the fastest rate of 265 words per minute.

step-by-step explanation:

it's a given that felicia reads at 260 word per minute and on connie's graph we can see that she reads 200 words per minute. since stew's table tells us that he read 795 in 3 minutes, we can divide 795 by 3 to find out how many words he reads per minute.

795/3 = 265

stew reads 265 words per minute - he reads at the fastest rate since felecia reads at 260 words per minute and connie reads at 200 words per minute.

stew (265) > felecia (260) > connie (200)