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3/5/24, 10:18 PM The Expert TA | Human-like Grading, Automated! https://usb06ca.theexpertta.com/Common/ViewAssignmentDetails.aspx 1/6 PHYS 8B (Spring 2024) Lowhorn Ch. 11 - Magnetic force Problem 1: The force on a loop of wire in a magnetic field shown in the figure can be used to measure the field strength. The field is uniform, and the plane of the loop is perpendicular to the field. Part (a) What is the direction of the net magnetic force on the loop? MultipleChoice : 1) Up 2) Left 3) Right 4) Out of the page. 5) Into the page. 6) Down Part (b) If a current of 4.5 A is used, what is the force generated per unit field strength on the 20.0 cm wide section of the loop? Use units of newtons per tesla. Numeric : A numeric value is expected and not an expression. F/B = __________________________________________ Problem 2: A rod of m = 0.25 kg and L = 0.45 m is on a ramp of two parallel rails with angle θ = 21 ° with respect to the horizontal. The current on the rod is I = 1.2 A, pointing into the screen as shown. A uniform magnetic field B = 0.85 T which points upward is applied in the region. The rod is initially at rest. Ignore the friction on the rails. Part (a) Express the magnitude of the magnetic force in terms of L , I and B . Expression : F B = __________________________________________ Select from the variables below to write your expression. Note that all variables may not be required. cos(θ) , sin(θ) , α , β , θ , B , d , F B , F n , g , h , I , L , m , t Part (b) Calculate the numerical value of the magnitude of the magnetic force in N. Numeric : A numeric value is expected and not an expression. F B = __________________________________________ Part (c) Which direction is the magnetic force? MultipleChoice :

3/5/24, 10:18 PM The Expert TA | Human-like Grading, Automated! https://usb06ca.theexpertta.com/Common/ViewAssignmentDetails.aspx 2/6 1) To the right. 2) To the left. 3) Into the screen. 4) Out of the screen. Part (d) Express the component of the magnetic force parallel to the ramp in terms of F B and θ . Expression : F p = __________________________________________ Select from the variables below to write your expression. Note that all variables may not be required. cos(α) , cos(φ) , cos(θ) , sin(α) , sin(φ) , sin(θ) , α , B , F B , F n , g , I , L , m , t Part (e) Express the component of the weight parallel to the ramp in terms of m , g and θ . Take up the ramp to be positive. Expression : F g = __________________________________________ Select from the variables below to write your expression. Note that all variables may not be required. cos(θ) , sin(θ) , α , β , θ , B , d , F B , F n , g , h , I , L , m , t Part (f) Calculate the numerical value of the net force F n parallel to the ramp, assuming the positive direction is up the ramp in N. Numeric : A numeric value is expected and not an expression. F n = __________________________________________ Part (g) Express the acceleration along the ramp in terms of the F n and m . Expression : a = __________________________________________ Select from the variables below to write your expression. Note that all variables may not be required. cos(θ) , sin(θ) , α , β , θ , B , d , F B , F n , g , h , I , L , m , t Part (h) Calculate the numerical value of a in m/s 2 . Numeric : A numeric value is expected and not an expression. a = __________________________________________ Part (i) If a is positive, which direction does the rod go? MultipleChoice : 1) Up the ramp. 2) Down the ramp. Part (j) If a is negative, which direction does the rod go? MultipleChoice : 1) Down the ramp. 2) Up the ramp. Problem 3: A negative charge of q = - 9.3 × 10 -17 C and m = 8.6 × 10 -26 kg enters a magnetic field B = 1.1 T with initial velocity v = 170 m/s, as shown in the figure. The magnetic field points into the screen. Randomized Variables q = - 9.3 × 10 -17 C m = 8.6 × 10 -26 kg B = 1.1 T v = 170 m/s

3/5/24, 10:18 PM The Expert TA | Human-like Grading, Automated! https://usb06ca.theexpertta.com/Common/ViewAssignmentDetails.aspx 4/6 Part (a) In which direction does the electric force act on the electrons? MultipleChoice : 1) To the left. 2) Upward. 3) To the right. 4) Downward. Part (b) In order to keep the electrons in a straight, horizontal line, in which direction should the magnetic force act? MultipleChoice : 1) Out of the screen. 2) To the right. 3) Into the screen. 4) To the left. 5) Downward. 6) Upward. Part (c) What should the direction of the magnetic field be in order to produce the force in part (b)? MultipleChoice : 1) Out of the screen. 2) Into the screen. Part (d) Express the magnitude of the electric force using the electric field E and the elementary charge e . Expression : F E = __________________________________________ Select from the variables below to write your expression. Note that all variables may not be required. B , e , E , g , m , v Part (e) Calculate the numerical value of the magnitude of the electric force in newtons. Numeric : A numeric value is expected and not an expression. = __________________________________________ N Part (f) Express the magnitude of the magnetic force in terms of the elementary charge , electron speed , and , the magnitude of the magnetic field. Expression : = __________________________________________ Select from the variables below to write your expression. Note that all variables may not be required. B , e , E , g , m , v Part (g) If the electron is continuing in a horizontal straight line, express the magnitude of the magnetic field in terms of and . Expression : = __________________________________________ Select from the variables below to write your expression. Note that all variables may not be required. B , e , E , g , m , v Part (h) Calculate the magnitude of the magnetic field in tesla, if the electron continues in a horizontal straight line. Numeric : A numeric value is expected and not an expression. = __________________________________________ T

3/5/24, 10:18 PM The Expert TA | Human-like Grading, Automated! https://usb06ca.theexpertta.com/Common/ViewAssignmentDetails.aspx 5/6 Problem 5: Consider the magnetic fields and velocities of charged particles shown in the figure. Part (a) What is the direction of the magnetic force on a positive charge that moves as shown in (a)? MultipleChoice : 1) Right 2) Into the page 3) Left 4) No force 5) Down 6) Up Part (b) What is the direction of the magnetic force on a positive charge that moves as shown in (b)? MultipleChoice : 1) right 2) left 3) into the page 4) no force 5) down 6) up Part (c) What is the direction of the magnetic force on a positive charge that moves as shown in (c)? MultipleChoice : 1) right 2) left 3) up 4) no force 5) down 6) into the page Part (d) What is the direction of the magnetic force on a positive charge that moves as shown in (d)? MultipleChoice : 1) right 2) left 3) no force 4) up 5) down 6) into the page Part (e) What is the direction of the magnetic force on a positive charge that moves as shown in (e)? MultipleChoice :