A student moves a horseshoe magnet by hand across a tabletop to varying distances from an electromagnet, as shown in the diagram above. The student records observations of how much force it takes to hold the horseshoe magnet in place at each distance. Observations

• 20 cm: no force required
• 10 cm: small force required; easy to hold in place
• 5 cm: large force required; very difficult to hold in place

What do the student's observations demonstrate?

A. The electromagnet's magnetic field becomes stronger as more magnetic material is added to it.

B. The electromagnet's magnetic field is stronger as more turns are added to the wire on the nail.

C. The electromagnet's magnetic field becomes stronger as a small amount of strength is added to the system by the battery.

D. The electromagnet's magnetic field is stronger close to it than far from it.

The closer together they are the harder it is to hold on to because the magnetic field is stronger as it gets closer.

D. The electromagnet's magnetic field is stronger close to it than far from it.

D

The electromagnet's magnetic field is stronger close to it than far from it.

Explanation:

Hope this helps!

  1.the balanced   chemical equation is as below

cu +   2 ag(no)₃ → cu(no₃)₂   +2 ag

2.the   much silver   produced   is   50.9 g

step 1: find the   moles of cu

moles =   mass÷   molar mass

  from periodic table the molar mass of cu = 63.5 g/mol

moles is therefore = 15.00 g÷ 63.5 g/mol = 0.236   moles

step 2: use the mole ratio to determine the   moles of ag

from equation above   cu: ag   is 1: 2

therefore the moles of ag   =0.236   moles   x 2/1 =0.472   moles

step 3: find the mass   of ag

mass = moles x molar mass

from periodic table   the molar mass of ag =107.87 g/mol

mass   = 0.472   moles x 107.87 g/mol = 50.9 g

3.   the   much   silver   collected worth is   1.797 oz

  convert   50.9 g   to oz

that is   1 gram = 0.0353 oz

          50.9 grams =?   oz

by cross multiplication

={(50.9 grams x 0.0353 oz) / 1   gram}   =1.797 oz

t = 1/400 h   ⇔ 0.0025 h ⇔ 9s ⇔ 0.15 m

any of the answers are correct.