If you have any questions, you are always welcome to contact us. We'll get back to you as soon as possible, withing 24 hours on weekdays.
Customer service
All questions about your order, return and delivery must be sent to our customer service team by e-mail at yourstore@yourdomain.com
Sale & Press
If you are interested in selling our products, need more information about our brand or wish to make a collaboration, please contact us at press@yourdomain.com
Help
If you have any questions, you are always welcome to contact us. We'll get back to you as soon as possible, withing 24 hours on weekdays.
Customer service
All questions about your order, return and delivery must be sent to our customer service team by e-mail at yourstore@yourdomain.com
Sale & Press
If you are interested in selling our products, need more information about our brand or wish to make a collaboration, please contact us at press@yourdomain.com
Electromagnetic theory is a peculiar subject. The peculiarity resides not so much in the stratification superposed layers of electrostatics. magnetostatics. steady currents and timevarying fields as in the failure that has attended all attempts to weld these layers into a logical whole. The lowest layer. electrostatics. defines certain concepts. such as E. D, ~, in a way that is generally satisfactory only for the static case. Yet the attempt is made to force these specialised definitions into the higher strata, with ad hoc modifications when necessary. The student, in looking through his text books on electromagnetics, can find general definitions only with difficulty. if at all; and even the most advanced treatises fail to present a rigorously logical development of the subject'. 1 So wrote Moon and Spencer some 30 years ago; and their criticism continues to be pertinent today. 2 More recently. a senior physicist of the National Bureau of Standards has expressed his concern in similar terms: 'A logically consistent set of definitions of the electromagnetic field quantities is extremely difficult to find in the literature. Most text books either evade the problem or present definitions that are applicable only to special cases'.
⚠️ WARNING (California Proposition 65):
This product may contain chemicals known to the State of California to cause cancer,
birth defects, or other reproductive harm.
<div class="dynamic-checkout__content" id="dynamic-checkout-cart" data-shopify="dynamic-checkout-cart"> <shopify-accelerated-checkout-cart wallet-configs="[{"name":"shop_pay","wallet_params":{"shopId":73758048501,"merchantName":"Ergodebooks","personalized":true}},{"name":"amazon_pay","wallet_params":{"checkoutLanguage":"en_US","ledgerCurrency":"USD","placement":"Cart","sandbox":false,"merchantId":"A1G1ZY975O1T6J","productType":"PayAndShip","design":"C0002"}},{"name":"paypal","wallet_params":{"shopId":73758048501,"countryCode":"US","merchantName":"Ergodebooks","phoneRequired":true,"companyRequired":false,"shippingType":"shipping","shopifyPaymentsEnabled":true,"hasManagedSellingPlanState":false,"requiresBillingAgreement":false,"merchantId":"L873BZSC9NMQS","sdkUrl":"https://www.paypal.com/sdk/js?components=buttons\u0026commit=false\u0026currency=USD\u0026locale=en_US\u0026client-id=AbasDhzlU0HbpiStJiN1KRJ_cNJJ7xYBip7JJoMO0GQpLi8ePNgdbLXkC7_KMeyTg8tnAKW4WKrh9qmf\u0026merchant-id=L873BZSC9NMQS\u0026intent=authorize"}}]" access-token="c0f52a66b386e9fa5c0ab4c2febc737c" buyer-country="US" buyer-locale="en" buyer-currency="USD" shop-id="73758048501" cart-id="1df30b2e8c63cbbe41d4e40a73809caa" enabled-flags="["ae0f5bf6"]" > <div class="wallet-button-wrapper"> <ul class='wallet-cart-grid wallet-cart-grid--skeleton' role="list" data-shopify-buttoncontainer="true"> <li data-testid='grid-cell' class='wallet-cart-button-container'><div class='wallet-cart-button wallet-cart-button__skeleton' role='button' disabled aria-hidden='true'> </div></li><li data-testid='grid-cell' class='wallet-cart-button-container'><div class='wallet-cart-button wallet-cart-button__skeleton' role='button' disabled aria-hidden='true'> </div></li><li data-testid='grid-cell' class='wallet-cart-button-container'><div class='wallet-cart-button wallet-cart-button__skeleton' role='button' disabled aria-hidden='true'> </div></li> </ul> </div> </shopify-accelerated-checkout-cart> <small id="shopify-buyer-consent" class="hidden" aria-hidden="true" data-consent-type="subscription"> One or more of the items in your cart is a recurring or deferred purchase. By continuing, I agree to the <span id="shopify-subscription-policy-button">cancellation policy</span> and authorize you to charge my payment method at the prices, frequency and dates listed on this page until my order is fulfilled or I cancel, if permitted. </small> </div>
Stay in the know
Subscribe to our newsletter and stay updated on latest offers, discounts and events near you.
For MAP (Minimum Advertised Price) violations, please contact:
map@ergode.com
For Intellectual Property (IP) or Trademark concerns, please contact:
ip@ergode.com
⚠️ California Proposition 65 Warning: Some products sold on this website may expose you to chemicals known to the State of California to cause cancer, birth defects, or other reproductive harm. For more information, visit www.P65Warnings.ca.gov.