Exam 15: Electric Forces and Fields

A ring of charge of radius r₀ lies in the x-y plane with its center at the origin.The charge counterclockwise from θ = 0º to θ = 180º is uniformly distributed with the total charge equaling Q.The charge counterclockwise from θ = 180º to θ = 360º is uniformly distributed with the total charge for this half of the ring equaling -Q.What is the direction of the electric field on the z-axis at the position (x,y,z)= (0,0,​r₀)?

If a charge +Q is placed inside a hollow isolated conductor that is originally neutral and the charge does not touch that conductor at any time:

We have an initially uncharged hollow metallic sphere with radius of 5.0 cm.I place a small object with a charge of +20 µC at the center of the sphere through a hole in the surface.Find the electric field present at a point 10 cm from the sphere's center.(k_e = 8.99 × 10⁹ N⋅m²/C²)​

If a negative charge is placed inside a hollow isolated conductor that is originally neutral and the charge does not touch that conductor at any time:

Two electrons are separated by 7.0 cm.What is the ratio of the electric force to the gravitational force between them? (m_e = 9.11 × 10−³¹ kg,k_e = 8.99 × 10⁹ N⋅m²/C²,G = 6.67 × 10^-11 N⋅m²/kg²,and e = 1.6 × 10−¹⁹ C)​

The combination of two separated point charges of opposite sign but equal magnitude is called an electric:

An airplane is flying through a thundercloud at a height of 2 500 m.(This is a very dangerous thing to do because of updrafts,turbulence,and the possibility of electric discharge. )If there is a charge concentration of +42 C at height 4 000 m within the cloud and −42 C at height 500 m,what is the magnitude of the electric field E at the aircraft? (k_e = 8.99 × 10⁹ N·m²/C²)

When charging two objects by rubbing them together

The average distance of the electron from the proton in the hydrogen atom is 0.65 × 10−¹⁰ m.What is the electric field from the proton's charge at the location of the electron? (k_e = 8.99 × 10⁹ N⋅m²/C²,e = 1.6 × 10−¹⁹ C)​

A proton initially moves left to right long the x axis at a speed of 9.0 × 10³ m/s.It moves into an electric field,which points in the negative x direction,and travels a distance of 0.8 m before coming to rest.If the proton's mass and charge are 1.67 × 10−²⁷ kg and 1.60 × 10−¹⁹ C respectively,what is the magnitude of the electric field?​

​A flat surface with area of 7.00 m² is oriented at an angle $\theta$ to a uniform electric field with magnitude 6.0 × 10⁵ N/C.If the flux through this surface is 2.0 × 10⁶ N.m²/C,what is $\theta$ ?

We have a hollow metallic sphere with charge −5.20 µC and radius 5.40 cm.We insert a +10.4-µC charge at the center of the sphere through a hole in the surface.What charge now rests on the outer surface of the sphere?​

An electron is sent at high speed toward a gold nucleus (charge +79e).What is the electrical force acting on the electron when it is 1.7 × 10−¹⁴ m away from the gold nucleus? (e = 1.6 × 10−¹⁹ C,k_e = 8.99 × 10⁹ N·m²/C²)​

Two small objects are suspended from threads.When the objects are moved close together,they attract one another.Which of the following could produce this result?

Two charges,+Q and −Q,are located two meters apart and there is a point along the line that is equidistant from the two charges as indicated.Which vector best represents the direction of the electric field at that point?

If body M,with a positive charge,is used to charge body N by induction,what will be the nature of the charge left on the latter?

A conducting spherical shell of inner radius And outer radius Has a charge Q on it.The flux through a concentric spherical surface of radius Is )An additional charge,also Q,is then added to the sphere.What is the change in flux through a concentric spherical surface of radius When the additional charge is placed on the conducting shell?

A proton moving at 3.0 × 10⁴ m/s is projected at an angle of 30° above a horizontal plane.If an electric field of 400 N/C is acting down,how long does it take the proton to return to the horizontal plane? (Hint: Ignore gravity.m_proton = 1.67 × 10−²⁷ kg,q_proton = 1.6 × 10−¹⁹ C)

If the size of the charge value is tripled for both of two point charges maintained at a constant separation,the mutual force between them will be changed by what factor?

Two identical spheres each carry a charge of −82.0 µC.The spheres are separated by a distance of 2.00 m.What is the electric force between the spheres? (k_e = 8.99 × 10⁹ N·m²/C²)​